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A HISTORY  OF  PSYCHOLOGY 


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A HISTORY  OF  PSYCHOLOGY 


BY 

OTTO  KLEMM 

EXTBAOBDINABY  PBOFESSOB  OF  PHILOSOPHY  IN  THE  UNIVEBSITY  OP  LEIPZIG 


AUTHORIZED  TRANSLATION  WITH  ANNOTATIONS 

BY 

EMIL  CARL  WILM,  Ph.D.,  LL.D. 

PBOFESSOB  OF  PHILOSOPHY  IN  WELLS  COLLEGE  AND  LECTDBEB  IN  PHILOSOPHY  AT 
BBYN  HAWB  COLLEGE  FOB  1914-15 

AND 

RUDOLF  PINTNER,  Ph.D. 

ASSISTANT  PROFESSOR  OF  PSYCHOLOGY  IN  THE  OHIO  STATE  UNIVERSITY 


70,  3 2 8 

CHARLES  SCRIBNER’S  SONS 


NEW  YORK 


CHICAGO 


BOSTON 


Copyright,  1914,  by 
CHARLES  SCRIBNER’S  SONS 


A 


PREFACE  FOR  THE  ENGLISH  EDITION 


The  following  work  is  a translation  of  Professor  Edemm’s 
Geschichte  der  Psychologie,  which  constitutes  Volume  VIII 
of  the  now  widely  known  series  “Science  and  Hypothesis.” 
As  a searching  study  of  an  enormously  wide  and  difficult  field 
the  original  German  work  has  already  won  for  itself  an  es- 
tablished place  in  the  recent  literature  of  the  subject,  and  it 
is  confidently  believed  that  the  qualities  which  have  given  the 
original  work  its  deserved  popularity,  the  author’s  equally 
firm  grasp  of  the  most  widely  separated  psychological  epochs 
and  tendencies,  his  admirable  attention  to  both  the  specu- 
lative and  the  scientific  aspects  of  psychology,  and,  finally, 
the  relative  prominence  given  to  recent  and  experimental 
psychology,  will  at  once  commend  the  work  to  the  large 
number  of  workers  in  modern  psychology  to  whom  English 
works  of  just  this  type  have  heretofore  not  been  available. 

The  work  of  translation  has  been  about  equally  divided 
between  the  two  translators,  Chapters  I-VI,  inclusive,  having 
been  executed  by  myself,  and  Chapters  VII-XII,  inclusive, 
by  Doctor  Pintner,  and  each  translator  is  solely  responsible 
for  the  final  form  in  which  his  own  part  of  the  work  appears. 

I wish  to  express  my  cordial  acknowledgments  to  Pro- 
fessor Miinsterberg,  to  whose  friendly  suggestion  the  plan 
for  this  translation  owed  its  first  inception,  and  to  Professor 
Titchener  for  a number  of  valued  suggestions  on  terminology. 


Bryn  Mawr  College, 

Bryn  Mawr,  Pa.,  October,  1914. 


E.  C.  WlLM. 


DO 


AUTHOR’S  PREFACE  FOR  THE  ENGLISH 
EDITION 


In  the  autumn  of  1911  I received  a letter  from  Doctor 
Wilm  informing  me  that  at  the  suggestion  of  Professor 
Munsterberg  he  was  maturing  plans  for  an  English  trans- 
lation of  my  History  of  Psychology,  and  requesting  my  co- 
operation. I very  gladly  granted  him  permission  for  such 
an  undertaking,  and  I have  since  then  had  much  pleasure, 
as  different  parts  of  the  translation  have  come  to  me,  in 
seeing  how  completely  he  and  his  excellent  collaborator, 
Doctor  Pintner,  have  overcome  one  after  another  the  mani- 
fold difficulties  which  such  a translation  presents. 

The  present  English  edition  is  making  its  appearance 
under  quite  different  circumstances  from  those  which  pre- 
vailed when  the  original  German  edition  went  into  print. 
I make  reference  in  the  course  of  the  book  to  the  irregular 
development  of  psychology.  The  history  of  psychology 
seems  to  be  undergoing  a development  of  a similar  sort. 
Although  the  triumphant  advance  of  the  experimental  method 
has  for  some  time  obscured  the  connection  of  modern  de- 
velopments with  the  earlier  epochs  of  our  science,  there  has 
recently  appeared  a whole  series  of  comprehensive  works 
on  the  history  of  psychology  to  which  the  valuable  additions 
to  my  own  bibliography  made  by  the  English  editor  bear 
testimony.  The  history  of  psychology  has  thus  itself  be- 
come a problem.  With  the  varied  treatment,  however, 
which  such  a wealth  of  material  permits,  one  of  these  works 
is  not  likely  to  crowd  out  another,  but  rather  to  supplement 

vii 


viii  AUTHOR’S  PREFACE  FOR  ENGLISH  EDITION 

and  enhance  it.  No  one,  in  any  case,  is  more  clearly  aware 
than  I that  my  own  selection  and  arrangement  of  the  material 
are  partly  determined  by  the  present  position  of  psychology 
in  my  own  country.  I do  not,  indeed,  see  how  it  could  be 
otherwise  in  the  case  of  a historical  presentation  which 
itself  extends  directly  into  the  present. 

May  I hope,  then,  that  my  little  book  will  also  find  read- 
ers beyond  the  sea  who  will  follow  in  it  the  fortunes  of  psy- 
chology among  its  sister  sciences  in  western  Europe,  and  that 
Doctor  Wilm  will  thus  find  himself  repaid  for  the  trouble 
and  care  for  which  I am  myself  permanently  indebted  to 
him ! 

Otto  Klemm. 

Leipzig,  June,  1914. 


CONTENTS 


INTRODUCTION 

PAGE 

1.  General  Characteristics  of  the  History  of  Psychology  1 

2.  Plan  of  the  Present  Work 2 

3.  Modern  and  Ancient  Elements  in  Psychology  ....  6 

4.  Literature 8 

Translators’  Note  on  English  Literature 10 

PART  I 

GENERAL  TENDENCIES  OP  PSYCHOLOGY 

I.  METAPHYSICAL  PSYCHOLOGY 
Chapter  I.  Dualism  in  Psychology 

1.  Relation  of  Metaphysical  and  Empirical  Tendencies  . 12 

2.  Dualistic  Psychology 14 

Chapter  II.  Monism  in  Psychology 

1.  Spiritualism 26 

2.  Materialism  in  Psychology 32 

(a)  Atomistic  Materialism  . 33 

( b ) Mechanistic  Materialism 36 

(c)  Psychophysical  Materialism 38 


IX 


X 


CONTENTS 


II.  EMPIRICAL  PSYCHOLOGY 
Chapter  III.  Descriptive  Psychology 

PAGE 

1.  Period  of  Pre-Scientific  Concepts  : The  Doctrine  of 

Mental  Faculties 44 

(a)  The  Doctrine  of  the  Parts  of  the  Soul 46 

(b)  The  Beginnings  of  Empirical  Psychology  in  Scholasticism  50 

(c)  The  Psychology  of  the  Renaissance 56 

( d ) The  Newer  Faculty  Psychology 58 

2.  The  Psychology  of  the  Inner  Sense 69 

(a)  The  Older  Doctrine  of  the  Inner  Sense 72 

( b ) The  Inner  Sense  as  an  Independent  Source  of  Experience  76 

(c)  The  Relation  of  Inner  Sense  to  Epistemological  Problems  82 

Chapter  IV.  Explanatory  Psychology 

1.  Association  Psychology 87 

(a)  The  Early  Beginnings  of  Association  Psychology  ...  88 

( b ) The  Dominance  of  the  Concept  of  Association  ....  92 

.2.  Psychology  as  a Mechanics  of  Ideas 103 

3.  Comparative  Psychology Ill 

(a)  Ethnic  Psychology Ill 

( b ) Animal  Psychology 113 

(c)  Influence  of  Darwinism 115 

(d)  Individual  Psychology 117 

4.  Influences  of  Natural  Science 119 

(a)  The  Newer  Phrenology 119 

(b)  The  Influence  of  Sense  Physiology 123 

(c)  Experimental  Psychology 127 


CONTENTS 


XI 


PART  II 

DEVELOPMENT  OF  THE  FUNDAMENTAL  CON- 
CEPTS  OF  PSYCHOLOGY 

Chapter  V.  The  Idea  of  Psychology  as  a Science 

PAGE 

1.  Older  Conceptual  Formulations  of  Psychology  . . . 147 

2.  The  Problem  of  a Science  of  Psychology 150 

3.  The  Modern  Concept  of  Psychology 155 

(a)  Psychology  and  Philosophy : Psychologism  and  Its 

Opponents 156 

( b ) Psychology  and  Natural  Science : Differentiation  of 

Physical  and  Psychical  Phenomena 159 

Chapter  VI.  The  Subject-Matter  of  Psychology:  Consciousness 

1.  The  History  of  the  Concept  of  Consciousness  . . . 166 

(а)  Early  Developments  of  the  Concept 166 

(б)  Development  of  the  Modern  Concept  of  Consciousness  . 169 

2.  The  Concept  of  the  Unconscious 172 

(a)  Representatives  and  Opponents  of  the  Notion  of  the 

Unconscious 172 

(b)  Arguments  for  and  against  the  Unconscious 175 

3.  The  Range  of  Consciousness 181 

4.  The  Graduation  of  Consciousness  : Attention  ....  184 

Chapter  VII.  Classification  of  the  Contents  of  Consciousness 

1.  Survey  of  the  Most  Important  Principles  of  Classi- 
fication   191 

(а)  The  Rise  of  Psychological  Classification 192 

(б)  The  Principle  of  Non-Deri vability 194 

(c)  The  Principle  of  Intentional  Relationship 200 

(d)  The  Principle  of  Analysis 202 


CONTENTS 


xii 

PAGE 

2.  Modern  Forms  of  Classification 205 

3.  The  Concept  of  the  Psychical  Element 210 

Chapter  VIII.  Psychological  Methods 

1.  Observation  and  Introspection 212 

2.  Physiology  the  Basis  of  Psychology 215 

3.  The  Development  of  the  Methods  of  Psychical  Mea- 

surement   218 

(a)  The  Older  Forms  of  the  Methods 220 

(i b ) The  Influence  of  the  Theory  of  Error 222 

(c)  Connection  with  the  Expression  Methods 229 

Chapter  IX.  Psychical  Measurement 

1.  Early  History  of  Psychical  Measurement 232 

(а)  The  Earliest  Suggestions  of  Psychical  Measurement  . . 233 

(б)  Weber’s  Law  and  Its  Preliminary  History 235 

2.  The  Founding  of  Psychical  Measurement  by  Fechner  . 242 

3.  Discussions  Arising  out  of  Fechner’s  Psychophysics  . 245 

(а)  Objections  and  Attacks 245 

(б)  Fechner’s  Reply 252 

(c)  Some  Philosophical  Opponents 254 

4.  The  New  Foundation  of  Psychical  Measurement  . . 257 

(a)  G.  E.  Muller’s  Foundation  of  Psychophysics  ....  257 

(b)  The  Psychological  Interpretation  of  Weber’s  Law  . . . 262 


CONTENTS 


xiii 

PART  III 

A HISTORY  OF  THE  MOST  IMPORTANT  PSYCHO- 
LOGICAL THEORIES 

Chapter  X.  Theories  of  Sensation 

PAGE 

1.  General  Theories  of  Sensation 271 

(a)  The  Older  Theories 273 

- (b)  The  Theory  of  Specific  Energy  of  the  Nerves  ....  275 

2.  Theories  of  Vision 279 

(a)  Ancient  Theories  of  Light 279 

( b ) Separation  of  Physical  and  Physiological  Optics  . . . 283 

(c)  Modern  Color  Theories 287 

(1)  The  Three-Color  Theory 290 

(2)  The  Four-Color  Theory : Opposition  and  Develop- 

ment   292 

3.  Theories  of  Audition 297 

(а)  Preliminary  History  of  the  Resonance  Theory  ....  297 

(б)  The  Theory  of  Resonance 299 

(c)  Further  Development  of  the  Resonance  Hypothesis  . . 304 

(d)  Consonance  Theories 308 

Chapter  XI.  Theories  of  Spatial  Perception 

1.  The  Natural  Scientists  of  the  Middle  Ages  ....  317 

2.  Some  Special  Problems 322 

3.  Nativism 326 

(a)  The  Founding  of  the  Theory  by  Johannes  Muller  . . . 326 

( b ) Its  Transference  to  the  Sense  of  Touch 327 

(c)  The  Later  Nativistic  Theories 330 


xiv  CONTENTS 

PAGE 

4.  Empiricism 333 

(a)  The  Origin  of  Empirical  Theories  of  Space 334 

(£>)  Helmholtz’s  Theory  of  Space 335 

5.  The  Genetic  Theories 337 

(a)  Herbart’s  Fusion  Theory 337 

( b ) Purely  Psychological  Theories 338 

(c)  The  Local  Sign  Theories 340 

(1)  Lotze’s  Theory 340 

(2)  Its  Physiological  Development  342 

(3)  Its  Psychological  Development 343 

Chapter  XII.  Theories  of  Feeling  and  Volition 

1.  Theories  of  Feeling 346 

(а)  Phenomenological  Presuppositions 347 

(б)  Intellectualistic  Theories  of  Feeling 350 

(c)  Psychomechanical  Theories  of  Feeling 352 

(d)  Physiological  Theories  of  Feeling 355 

(c)  Psychophysical  Theories  of  Feeling 358 

2.  Theories  of  Volition 359 

(a)  Intellectualistic  Theories  of  Volition 361 

(1)  The  Ancient  Concept  of  Freedom 361 

(2)  The  Primacy  of  Will  or  Intellect 362 

(3)  The  Classical  Period  of  the  Problem  of  the  Freedom 

of  the  Will 364 

( b ) The  Absolute  Theory  of  the  Will 366 

(c)  Heterogenetic  Theories  of  the  Will 368 

(d)  The  Emotional  Theory  of  the  Will 370 

Index  of  Names 373 

Index  of  Subjects 379 


A HISTORY  OF  PSYCHOLOGY 


A HISTORY  OF  PSYCHOLOGY 


INTRODUCTION 

1.  General  Characteristics  of  the  History  of 
Psychology 

A contemporary  psychologist  has  said  that  psychology 
has  had  a long  past  but  a brief  history.  Scattered  reflec- 
tions on  psychological  questions  indeed  abound  throughout 
the  entire  history  of  science,  but  the  continuity  of  psycho- 
logical investigation  has  often  been  interrupted,  while  a 
really  fruitful  development  of  psychology  belongs  to  very 
recent  times. 

With  this  the  extreme  complexity  of  mental  processes,  a 
complexity  which  seems  only  to  increase  the  more  intimately 
we  come  to  know  them,  has  had  no  little  to  do.  There  is 
something  in  the  very  nature  of  mental  processes,  even  in 
their  simpler  forms,  which  resists  the  attempt  to  subject 
them  to  scientific  treatment.  In  the  first  place,  they  do  not 
constitute  a special  group  of  facts  which  can  be  unambigu- 
ously distinguished  from  other  groups  of  facts,  and  which 
perhaps  have  to  be  discovered.  They  are  constantly  with 
us;  indeed,  every  fact  is  in  part,  or  on  one  of  its  sides,  a 
mental  fact.  Moreover,  the  facts  of  consciousness  are  not 
data  which  are  discovered  like  a rare  mineral  or  which  can 
be  observed  like  an  unfamiliar  phenomenon  in  nature.  Long 
before  these  facts  are  subjected  to  scientific  analysis  they 
have  been  subjected  to  innumerable  influences  of  social  life. 
Language,  for  example,  to  mention  only  the  most  important 

1 


2 


HISTORY  OF  PSYCHOLOGY 


of  these  influences,  has  already  appropriated  them,  has  de- 
scribed them,  and  has  interpreted  them  according  to  the 
needs  of  practical  life.  There  is  a further  peculiarity  of  the 
material  of  psychology  which  makes  the  scientific  investi- 
gation of  it  especially  difficult.  In  all  scientific  investiga- 
tion a certain  emotional  detachment  would  seem  to  be  abso- 
lutely necessary  for  the  success  of  the  scientific  enterprise. 
But  in  psychology  the  feelings  and  emotions  become  them- 
selves objects  of  investigation,  and  the  most  central  questions 
of  psychology  are  intimately  related  to  the  important  inter- 
ests of  our  common  life.  It  is  true  that  even  in  the  physical 
sciences  the  methods  of  investigation  have  only  gradually 
been  freed  from  the  subjective  interference  of  feeling.  It  is 
told  of  no  less  an  observer  than  Galileo  that  he  was  so  irri- 
tated by  the  inexplicable  changes  in  the  form  of  Saturn,  due 
to  the  position  of  its  rings,  which  were  at  the  time  still  un- 
known to  him,  that  he  refused  to  observe  this  planet  at  all. 
How  much  more  difficult  must  it  be  for  psychology  to  fulfil 
the  demands  of  purely  objective  observation  when  its  funda- 
mental problems  are  so  deeply  interwoven  with  man’s  deep- 
est interests,  hopes,  and  passions!  It  is  only  a consequence 
of  these  circumstances  that  psychology  has  undergone  a dif- 
ferent historical  development  from  that  of  cognate  sciences 
and  that  the  historical  account  of  its  development  must  fol- 
low its  own  more  or  less  unique  methods.1 

2.  Plan  of  the  Present  Work 

One  of  the  most  notable  differences  between  the  develop- 
ment of  psychology  and  that  of  the  other  empirical  sciences, 
particularly  the  natural  sciences,  lies  in  the  relation  between 
the  two  stages  of  development  which  we  may  call  the  prac- 

1Cf.  Ebbinghaus,  “Psychologie,”  in  Kuliur  der  Gegenwart,  I,  62,  1908, 

pp.  173  Jf. 


INTRODUCTION 


3 


tical  and  the  purely  observational  or  descriptive.  Most  of 
the  sciences  which  we  to-day  class  as  descriptive  sciences  had 
as  their  original  aim  some  sort  of  control  over  nature  and 
fortune.  Man  does  not  at  first  observe  the  processes  of 
nature  in  the  midst  of  which  he  fives  merely  for  their  own 
sake;  he  rather  observes  them  in  order  that  he  may  himself 
influence  and  control  them  in  the  interests  of  his  own  needs  . 
and  purposes.  Thus  astrology,  which  sought  to  afford  gui- 
dance in  conduct  through  the  prognostication  of  events,  be- 
came astronomy;  alchemy,  which  had  as  its  object  the  arti- 
ficial production  of  precious  metals,  became  chemistry,  and 
so  on.  Following  up  this  analogy,  one  would  be  led  to  look 
for  the  antecedents  of  modern  psychology  in  chiromancy,  in 
mnemotechnics,  and  in  witchcraft,  which  plays  such  an  impor- 
tant role  even  with  so  thoroughgoing  an  empiricist  as  Bacon. 
These  occult  sciences,  however,  which  are  obviously  the  ante- 
cedents of  modern  spiritism,  have  borne  little  or  no  relation 
to  the  scientific  analysis  of  mental  fife.  It  is  true  that  we 
find  in  modern  times  many  attempts  to  give  explanations  of 
spiritistic  phenomena  which  lay  claim  to  scientific  status. 
Count  Gasparin,  for  example,  attempts  to  explain  spiritistic 
phenomena  by  reference  to  a fluid,  called  “psychode”  by 
Thury,  which  is  subject  to  voluntary  control.  And  between 
the  wholly  transcendental  explanation  of  the  astronomer 
Porro,  with  his  hypothesis  of  a divided  personality,  and  the 
pseudo-empirical  view  of  Maxwell  that  spiritistic  phenomena 
are  to  be  explained  by  the  collective  consciousness  of  the 
participants  in  the  psychic  experiment,  there  is  a whole  series 
of  more  or  less  fantastic  attempts  to  extend  the  concepts  and 
categories  of  modern  psychology  to  the  realm  in  question.1 
But  the  transition  from  the  practical  to  the  purely  observa- 

1 The  more  important  of  these  attempts  at  explanation  have  been 
compiled  by  Camille  Flammarion  in  Unbekannte  Naturhrafte;  German 
translation  by  Michalski,  1908,  p.  343. 


4 


HISTORY  OF  PSYCHOLOGY 


tional  stage,  so  characteristic  of  the  natural  sciences,  evi- 
dently does  not  repeat  itself  here. 

It  is  due  to  the  very  nature  of  the  contents  of  consciousness 
that  their  scientific  study  has  profited  but  little  from  contact 
with  the  species  of  practical  psychology  referred  to  above, 
and  that  such  study  could  prosper  only  within  the  bounds 
of  a world  view  in  which  theoretical  motives  predominate  or 
in  which,  at  any  rate,  practical  motives  are  moderated  by 
contact  with  ethical  or  religious  needs  and  interests.  Thus 
the  meagre  practical  application  of  psychology  which  the  his- 
tory of  this  science  reveals  would  also  find  its  explanation. 
While,  then,  on  the  one  hand,  scientific  psychology  owes  little 
to  the  doubtful  successes  of  the  occult  sciences,  based  upon 
an  alleged  knowledge  of  mental  life,  scientific  psychology  has, 
on  the  other  hand,  rather  persistently  declined  to  take  any 
interest  in  the  practical  problems  of  the  occult.  The  alliance 
which  has  for  a considerable  period  been  established  between 
psychology  and  pedagogy  seems,  indeed,  to  promise  well  for 
the  future.  If  psychology  is  ever  to  become  a practical  sci- 
ence it  will  become  such  by  entering  the  fields  of  pedagogy, 
law,  and  medicine,  fields  which  have,  indeed,  already  been 
opened  to  modern  psychology.  And  when  one  compares 
the  success  of  psychology  in  these  fields  with  the  success  of 
the  natural  sciences  in  their  various  applications,  the  com- 
parative recency  of  psychology  as  a theoretical  science  must 
not  be  lost  sight  of.1  From  these  changes  in  the  point  of 
view  adopted  by  psychology  result  a number  of  general  psy- 
chological tendencies  which  we  shall  seek  to  review  in  the 
first  chapter  of  this  book. 

The  development  of  opinion  regarding  principial  questions 
in  psychology,  as  exhibited  in  certain  fundamental  psycho- 
logical concepts,  has  a certain  historical  continuity  of  its  own. 

1 Cf.  Wundt,  “Uber  reine  und  angewandtePsychologie,”  Psychologische 
Studien,  V,  pp.  1 ff. 


INTRODUCTION 


5 


In  this  respect,  too,  psychology  differs  characteristically  from 
the  natural  sciences.  Theories  regarding  the  connections  of 
external  phenomena  appear  comparatively  early  in  the  his- 
tory of  civilization.  The  antithesis  between  the  teleological 
and  the  mechanical  views  of  nature,  for  example,  is  already 
clearly  presented  in  the  writings  of  Aristotle  and  Democritus, 
and  the  antithesis  has  persisted  throughout  the  whole  subse- 
quent history  of  science.  Principles  of  a similar  nature  ap- 
pear much  later  in  the  history  of  psychology.  The  inner  life 
of  man  was  not  only  not  an  immediate  object  of  theoretical 
investigation,  but  it  was  from  the  outset  subjected  to  the  in- 
fluence of  ethical  and  religious  ideas.  While  the  task  of  nat- 
ural science  was  merely  to  subject  recognized  phenomena  to 
scientific  treatment  and  interpretation,  psychology  was  first 
obliged  to  bring  the  phenomena  with  which  it  dealt  into  con- 
scious existence.  The  act  of  willing,  for  example,  which  ap- 
peared in  the  first  place  as  either  good  or  bad,  had  to  be 
viewed  as  a pure  experience,  without  reference,  that  is,  to 
its  ethical  or  social  significance;  or  the  features  which  are 
common  to  a sensation,  as  a cognitive  process  and,  say,  a 
feeling  of  pleasantness  had  to  be  determined,  etc.  It  is  such 
efforts  as  these  that  we  shall  seek  to  follow  in  our  second 
chapter,  which  deals  with  the  fundamental  concepts  of  psy- 
chology. 

Finally,  there  have  arisen  in  connection  with  a number  of 
psychological  problems,  such  as  sense-perception,  volition, 
etc.,  certain  theories  which  cannot  always  be  readily  fitted 
into  the  framework  of  a systematic  psychology,  but  which 
can  be  treated  historically,  since  it  is  the  same  problems 
which  persist  throughout  all  the  metamorphoses  which  their 
explanations  undergo.  We  shall,  of  course,  understand  by 
the  phrase  “psychological  theories”  only  such  concepts  and 
principles  as  are  able  to  meet  the  demand  which  every  sci- 
entific theory  must  meet,  viz.,  that  it  shall  connect  phenom- 


6 


HISTORY  OF  PSYCHOLOGY 


ena  with  their  causes  in  accordance  with  natural  laws.  The 
older  doctrine  of  mind-stuff,  for  example,  is  not  a psycholog- 
ical theory  but  a metaphysical  interpretation  of  mental  phe- 
nomena. The  history  of  the  most  important  of  these  psy- 
chological theories  will  be  dealt  with  in  the  final  chapter. 

Since  the  development  of  psychology  is  but  a phase  of 
intellectual  development  in  general,  it  would  doubtless  be 
possible  to  identify  in  psychology  the  same  general  stages 
through  which  the  history  of  intellectual  culture  has  passed. 
The  attempt,  however,  to  deduce  from  the  latter  the  laws 
for  the  historical  development  of  psychology  would  be  fruit- 
ful only  for  special  tendencies  or  problems  of  psychology  or 
else  it  would  lose  itself  in  unprofitable  generalities.  As  an 
example  of  the  latter  we  might  cite  the  three  organic  laws 
for  the  development  of  psychology  enumerated  by  Maurice 
de  Wulf,1  which,  however,  tell  us  nothing  more  than  that 
psychology  passes  from  a dogmatic  through  a critical  stage 
in  order  to  complete  its  development  when  the  human  spirit 
itself  reaches  its  maturity.  It  has  seemed  to  us  a more 
interesting  and  attractive  task  simply  to  follow  the  move- 
ment of  history  and  to  separate  out  from  the  broad  stream 
of  tradition  those  ideas  which  appeared  significant  and 
which  are  sometimes  so  much  in  advance  of  their  time  that 
we  feel  a sense  of  kinship  with  bygone  thinkers  as  if  they 
belonged  to  our  own  time. 

3.  Modern  and  Ancient  Elements  in  Psychology 

The  principal  aim  of  the  present  treatise  is  to  trace  modern 
psychology  back  to  its  historical  antecedents.  Anticipations 
of  modern  psychology  are,  of  course,  to  be  found  at  all  stages 
of  the  history  of  the  science;  in  fact,  the  order  of  ancient  and 

1 “Les  lois  organiques  de  l’histoire  de  la  psychologie,”  Archiv  f.  Gesch. 
d.  Phil.,  X,  1897,  pp.  393  ff. 


INTRODUCTION 


7 


modern  is  not  seldom  curiously  reversed.  Who,  for  example, 
does  not  find  in  Alhacen’s  Optics,  published  in  1269,  a mode 
of  thinking  more  akin  to  our  own  than  that  contained  in 
many  of  the  speculations  of  the  school  of  Schelling  concerning 
the  alleged  analogies  between  sense  qualities  and  the  mode 
of  appearance  of  physical  forces?  And  if  we  go  back  still 
further  we  shall  find  a form  of  mental  mechanics  in  Aristotle 
which,  as  an  anticipation  of  modern  explanatory  psychology, 
ranks  far  above  the  Wolffian  faculty  psychology  of  the 
eighteenth  century. 

It  is  difficult,  accordingly,  to  assign  with  much  confidence 
a date  at  which  modern  psychology  may  properly  be  said  to 
begin.  There  is  hardly  a division  point  in  the  history  of 
philosophy  which  may  not  also,  from  some  point  of  view,  be 
regarded  as  the  beginning  of  modern  psychology.  If  one  is 
thinking  of  psychology  as  an  exact,  experimental  science, 
developing  in  close  relation  to  physiology,  then  modern  psy- 
chology may  be  said  to  date  from  the  middle  of  the  nine- 
teenth century.  Frequently  the  empirical  psychology  of  the 
eighteenth  century,  in  which  individual  psychology  and  psy- 
chiatry were  closely  connected  interests,  is  pointed  out  as  a 
mode  of  thinking  which  is  related  to  our  own.  John  Locke, 
the  founder  of  the  so-called  psychology  of  the  inner  sense,  is 
usually  named  as  the  founder  of  modern  empirical  psychol- 
ogy, thus  placing  the  beginning  of  modern  psychology  near 
the  end  of  the  seventeenth  century.  Again,  the  significance 
which  Descartes’  definition  of  consciousness  assumed  for 
psychology  has  been  thought  sufficient  to  make  the  Car- 
tesian system  the  dividing  point  between  ancient  and  modern 
psychology.  Still  further  back  do  we  find  empirical  psy- 
chology explicitly  contrasted  with  the  traditional  meta- 
physical psychology,  as  by  Ludovicus  Vives,  who  has  him- 
self been  called  the  father  of  modern  psychology,  thus  placing 
the  beginning  of  the  science  in  the  first  half  of  the  sixteenth 


8 


HISTORY  OF  PSYCHOLOGY 


century.  Siebeck’s  researches,  finally,  have  detected  the 
fruitful  beginnings  of  empirical  psychology  in  Scholasticism. 
Observations  on  certain  striking  color  phenomena  are  utilized 
for  illustrative  purposes  in  the  theological  tractates  of  the 
followers  of  Eckhart,  which  exact  psychology  has  been  very 
tardy  in  taking  into  account.  Although  these  beginnings  of 
empirical  psychology  consist  mainly  in  a departure  from  the 
Aristotelian  tradition,  it  must  not  be  forgotten  that  the 
Aristotelian  writings  contain  anticipations  which  extend 
into  the  most  modern  times. 

Although,  therefore,  our  task  takes  us  back  into  the  re- 
motest antiquity,  the  history  of  psychology,  perhaps  more 
than  the  history  of  any  other  science,  falls  into  periods  and 
epochs  in  which  scattered  ideas  of  real  significance  stand 
out  in  clear  relief  against  a colorless  mass  of  traditional 
learning.  A proper  historical  appreciation  of  such  phenomena 
is  often  made  difficult  by  the  exaggerated  estimate  of  some 
single  thinker,  like  Aristotle,  for  example,  who  is  often  said 
to  have  had  only  predecessors  and  imitators.  Some  such 
remark  might,  indeed,  apply  to  certain  ideas  in  the  history 
of  science,  particularly  in  the  history  of  psychology  of  which 
it  can  truly  be  said  that  they  have  had  only  anticipations 
and  developments. 


4.  Literature 

The  first  attempt  to  write  the  history  of  psychology  was 
made  by  Aristotle  {Be  Anima,  I,  2).  But  it  is  not  until  the 
historical  sense  is  awakened  by  Romanticism  that  the  study 
of  the  history  of  psychology  begins.  The  most  notable  work 
which  has  come  down  to  us  from  this  period,  a book  which 
is  still  instructive  on  many  points,  is  F.  A.  Carus’s  Geschichte 
der  Psychologie,  published  in  1808. 

If  we  confine  ourselves  to  the  one  most  important  modern 


INTRODUCTION 


9 


work  for  the  discussion  of  any  given  period,  the  most  ex- 
haustive work  on  the  history  of  ancient  psychology  down  to 
Thomas  Aquinas  is  H.  Siebeck’s  Geschichte  der  Psychologie 
(1880-4),  which  is  supplemented  by  a series  of  articles  on 
scholastic  psychology,  published  in  Archiv  fur  die  Geschichte 
der  Philosophic,  I— III  (1888-90).  No  work  of  similar  scope 
and  value  exists  for  the  period  of  the  Renaissance  and 
for  the  metaphysical  systems  of  the  sixteenth  century.  In 
fact,  there  is  no  other  period  in  which  scientific  psychology 
breaks  up  into  so  many  scattered  observations  and  unrelated 
points  of  view.  The  most  complete  account  of  the  period 
from  Leibniz  to  Kant  is  contained  in  Dessoir’s  Geschichte  der 
neueren  deutschen  Psychologie,  part  I (2d  ed.,  1902).  The 
main  problems  of  the  history  of  psychology  in  the  nineteenth 
century  are  treated,  very  unevenly,  to  be  sure,  by  Eduard 
von  Hartmann,  in  his  Die  moderne  Psychologie,  1901  (Werke, 
XIII).  A circumstantial  account  of  the  more  modern  ten- 
dencies of  psychology  is  to  be  found  in  Ribot’s  Psychologie 
anglaise  contemporaine  (2d  ed.,  1875),  and  Psychologie  alle- 
mande  contemporaine  (2d  ed.,  1885).  The  points  of  view, 
finally,  wdiich  have  dominated  the  developments  of  experi- 
mental psychology  have  been  briefly  summarized  by  Wundt 
in  his  article  “Psychologie,”  contained  in  the  Kuno  Fischer 
Festschrift,  Die  Philosophie  im  Beginn  des  20.  Jahrhunderts 
(2d  ed.,  1906).  Among  the  works  on  systematic  psychology 
Volkmann’s  Lehrbuch  der  Psychologie  (4th  ed.,  1894-5) 
contains  a wealth  of  historical  references  and  excursions 
which  is  worthy  of  admiration  even  to-day. 

With  neither  of  these  works,  each  of  which  is  based  upon 
an  extensive  literature  in  the  form  of  monographs  and  special 
investigations,  does  the  present  book  wish  to  enter  into  com- 
petition. It  rather  presupposes  them,  as  it  does  the  study 
of  the  sources,  and  it  should  be  supplemented  by  references 
to  them.  Siebeck’s  and  Dessoir’s  books,  particularly,  are 


10 


HISTORY  OF  PSYCHOLOGY 


utilized  extensively  in  the  treatment  of  ancient  psychology 
and  the  psychology  of  the  Enlightenment,  respectively.  But 
the  writer  does  hope  that  the  treatment  of  psychology  in  its 
historical  development  will  exhibit  the  problems  of  contem- 
porary psychology  in  their  genesis  and  will  thus  prepare 
the  way  for  their  independent  study  and  treatment.  At  a 
time  when  psychology  is  taking  her  place  as  an  independent 
empirical  science  among  her  sister  sciences  such  a treatment 
will,  perhaps,  help  to  obviate  certain  misunderstandings  such 
as  are  illustrated  in  profusion  in  the  attempt  of  a brilliant 
contemporary  writer  to  prove  that  psychology  is  quite  with- 
out prospects.  In  thus  tracing  the  development  of  psy- 
chological reflection,  certain  border  problems  occupy  atten- 
tion perhaps  somewhat  more  than  their  importance  may 
seem  to  warrant  at  a time  when  psychology  is  taking  her 
place  among  the  other  sciences  as  a special  empirical  science. 
In  the  history  of  psychology,  however,  the  border  lines  be- 
tween science  and  hypothesis  have  always  been  obscure.  It 
is  the  hypothetical  element  in  psychology,  in  fact,  which  has 
invested  psychological  problems  with  peculiar  interest  and 
vitality.  One  is  reminded  here  of  the  statement  of  Poincare 
that  the  growth  of  a science  occurs  along  its  borders. 

Translators’  Note  on  English  Literature 

The  reader  may  also  be  referred  to  the  following  works  on 
the  history  of  psychology  which  have  appeared  in  English 
either  as  original  works  or  as  translations: 

Baldwin,  J.  M.,  History  of  Psychology,  New  York  and 
London,  1913. 

Brett,  G.  S.,  A History  of  Psychology,  London,  1912. 

Dessoir,  M.,  Outlines  of  the  History  of  Psychology,  tr.  of 
Abriss  einer  Geschichte  der  Psychologie,  by  Donald  Fisher, 
New  York,  1912. 


INTRODUCTION 


11 


Ribot,  Th.,  English  Psychology,  tr.  of  the  work  cited  above, 
by  J.  M.  Baldwin,  New  York,  1897. 

Ribot,  Th.,  German  Psychology  of  To-Day,  tr.  of  the  work 
cited  above,  by  J.  M.  Baldwin,  New  York,  1899. 


PART  1 


GENERAL  TENDENCIES  OF  PSYCHOLOGY 

I.  METAPHYSICAL  PSYCHOLOGY 

CHAPTER  I 

DUALISM  IN  PSYCHOLOGY 
i.  Relation  of  Metaphysical  and  Empirical  Tendencies 

Although  psychical  phenomena  are  of  all  data  the  most 
accessible,  the  history  of  psychology  bears  witness  to  the 
extreme  difficulty  of  gaining  the  proper  point  of  view  for  the 
study  of  the  phenomena  in  question.  Psychology,  indeed, 
appears  surprisingly  early  as  one  among  the  other  sciences, 
but  for  centuries  psychology  does  little  more  than  reflect 
the  presuppositions  and  conclusions  of  philosophy.  When 
the  points  of  view  of  a metaphysical  world  view  are  trans- 
ferred to  the  realm  of  conscious  phenomena,  the  latter 
appear  as  manifestations  or  modes  of  activity  of  a soul, 
an  entity  usually  thought  of  as  substantial.  The  particular 
phenomena  of  consciousness  are  deduced  from  the  concep- 
tual definition  of  the  soul.  Side  by  side  with  metaphysi- 
cal psychology  appears  empirical  psychology  which  makes 
psychical  phenomena  objects  of  introspection,  and  seeks 
to  exhibit  their  scientific  connection.  The  metaphysical 
and  the  empirical  tendencies  are  by  no  means  mutually  ex- 
clusive. Empirical  materials  are  to  some  extent  utilized  in 
every  type  of  metaphysical  psychology,  and  empirical  psy- 
chology, on  the  other  hand,  gives  rise  to  problems  which 

12 


DUALISM  IN  PSYCHOLOGY 


13 


properly  belong  to  metaphysics.  In  this  respect  psychology 
does  not  differ  from  the  rest  of  the  factual  sciences.  And  if 
metaphysical  problems  arise  more  inevitably  in  psychology 
than  in  some  of  the  other  sciences,  it  is  doubtless  due  to  the 
close  affinity  between  the  subjective  mode  of  viewing  the 
contents  of  consciousness  and  the  reflection  upon  the  move- 
ments of  the  inner  life  which  so  naturally  carries  one  forward 
to  a metaphysical  view  of  existence. 

The  various  tendencies  within  metaphysical  psychology 
exhibit  a close  resemblance  in  the  manner  in  which  psychical 
phenomena  are  deduced  from  the  concept  of  the  soul,  the 
difference  appearing  in  the  definition  of  the  soul  itself.  The 
empirical  tendencies  start  with  the  same  method,  that  of 
introspection;  they  differ  from  each  other  mainly  in  the 
principles  e~  ployed  in  the  interpretation  of  the  data  which 
introspection  reveals.1 

The  oldest  forms  of  metaphysical  psychology  were  domi- 
nated by  categories  developed  within  the  domain  of  natural 
science,  from  which  they  were  transferred  to  the  realm  of 
the  inner  life.  The  soul,  accordingly,  appears  as  an  entity, 
a substance,  corresponding  to  substances  and  things  in  the 
external  world.  There  occurs  thus  a complete  reversal  of 
the  more  familiar  anthropomorphic  modes  of  thinking: 
psychical  facts,  in  order  that  they  may  be  thought  real  at 
all,  are  brought  under  concepts  originally  derived  from  the 
domain  of  external  nature. 

The  contrasts  between  spirit  and  matter  familiar  in  meta- 
physical systems  thus  reappear  in  psychology  in  the  specula- 
tions concerning  the  nature  of  the  soul.  The  most  natural  con- 
ception here  is  dualism,  which  opposes  material  substance  and 
soul  substance.  Attempts  to  transcend  this  antithesis  lead 

1 These  and  a number  of  subsequent  distinctions  are  drawn  from 
Wundt’s  Grundriss  der  Psychologies  1909.  [English  tr.  by  C.  H.  Judd, 
Outlines  of  Psychology,  2d  ed.,  L'ipzig,  1902.  Trs.] 


14 


HISTORY  OF  PSYCHOLOGY 


to  spiritualistic  psychology,  in  which  physical  processes  are 
held  to  be  essentially  identical  with  psychical  processes,  and 
materialistic  psychology,  in  which  psychical  processes  are  held 
to  be  merely  a mode  or  a manifestation  of  matter. 

2.  Dualistic  Psychology 

Dualism  results  from  the  introduction  of  prescientific 
ideas  into  the  whole  of  a world  view  in  which  the  phenomena 
of  reality  have  been  subjected  to  little  or  no  interpretation. 
For  primitive  thought,  man,  like  everything  else  in  the 
world,  is  a composite  of  body  and  soul.  As  knowledge  in- 
creases, many  objects  are  bereft  of  soul  life,  so  that  event- 
ually only  living  beings  remain  endowed  with  psychical 
qualities.  These  conceptions  of  primitive  peoples  form  the 
subject-matter  of  folk  psychology.  They  are  of  interest  to 
the  history  of  psychology,  since  they  have  been  made  the 
objects  of  conscious  reflection  and  have  been  raised  to  the 
dignity  of  psychological  theories.  From  the  earliest  repre- 
sentatives of  Oriental  philosophy  to  the  time  of  Plato  we 
find  a primitive  dualism  which  teaches  that  the  soul  leads 
only  a shadowy  existence  after  its  separation  from  the  body. 

The  first  attempt  to  give  a connected  account  of  mental 
phenomena  within  the  framework  of  a metaphysical  world 
view  is  made  by  Heraclitus  of  Ephesus.  The  system  of 
Heraclitus,  like  that  of  his  predecessors,  is  monistic  in  the 
primitive  sense  of  the  term.  All  things,  including  the  soul, 
originate  from  fire,  the  soul  appearing  at  that  stage  of  the 
evolution  of  the  universal  element  where  the  latter  breaks 
up  into  earth  and  fiery  vapor.  In  the  human  organism  the 
body  represents  the  earthy,  the  soul  the  fiery  element. 
Through  the  breath  it  partakes  of  the  warm  air  and  thus 
of  the  same  rationality  as  fire  is  supposed  to  possess.  Its 
origination  and  destruction  are  merely  phases  of  the  general 


DUALISM  IN  PSYCHOLOGY 


15 


rhythmic  movement  of  existence:  “It  is  death  to  souls  to 
become  water,  and  death  to  water  to  become  earth.  But 
water  comes  from  earth;  and  from  water,  soul.”  The  ex- 
perienced difference  between  body  and  soul  Heraclitus  ex- 
plains by  the  hypothesis  that  they  represent  two  stages  in 
the  development  of  fire.  The  knowledge  of  the  soul  accord- 
ingly presupposes  a knowledge  of  reality  as  a whole.  Like 
the  universe,  it  is  unfathomable,  as  the  well-known  saying 
testifies:  “You  will  not  find  the  boundaries  of  soul  by  trav- 
elling in  any  direction.”  1 

It  is  not  until  we  come  to  Empedocles  of  Agrigentum  that 
Ionic  hylozoism  becomes  consistently  dualistic.  It  is  true 
that  Empedocles  reduces  all  becoming  to  relationships  of 
matter  and  force.  Matter  is  composed  of  four  elements, 
while  force  manifests  itself  in  the  interplay  of  attraction  and 
repulsion,  figuratively  called  love  and  hate.  The  soul,  how- 
ever, is  not  affected  by  these  physical  theories.  The  hypoth- 
eses of  the  philosophy  of  nature  that  the  soul,  like  everything 
else,  consists  of  the  various  elements  combined  in  the  proper 
proportions  become  mingled  with  religious  ideas  according 
to  which  the  individual  soul  is  merely  a part  of  the  world 
soul.  The  elements  themselves  are  now  transformed  into 
divinities;  the  soul  is  capable  of  an  existence  separate  from 
matter,  and  the  doctrine  of  metempsychosis  clearly  indicates 
contact  with  Pythagorean  ideas.  Pythagorean  psychology, 
from  all  we  are  able  to  ascertain  concerning  the  matter,  was 
also  dualistic  in  character.  The  saying  that  the  soul  is  a 
harmony,  or  possesses  harmony,  was  already  within  the 
Pythagorean  school  a statement  of  equivocal  significance. 
It  is  beyond  question,  however,  that  the  dualism  of  body 
and  soul  was  for  the  Pythagoreans  merely  a repetition  of  the 
familiar  antithesis  between  the  unlimited  and  the  limited, 
between  matter  and  force. 

1 [Burnet,  Early  Greek  Philosophy,  p.  138.  Trs.] 


16 


HISTORY  OF  PSYCHOLOGY 


A new  form  of  dualism,  in  which  the  priority  of  spirit  over 
matter  first  received  recognition,  is  represented  by  Anaxag- 
oras. To  the  indistinguishable  mixture  of  all  things,  which 
represents  the  material  world,  is  opposed  a homogeneous  and 
independent  principle  which  furnishes  the  condition  of  mo- 
tion. This  principle  of  movement  is  at  the  same  time  a 
principle  of  order  and  intelligence  (vou?).  In  the  descrip- 
tion of  the  vow  a tendency  toward  pure  spiritualism  makes 
itself  felt.  It  is  unmixed,  unitary,  and  free  from  suffering.  It 
is  self-governing;  it  possesses  all  knowledge  and  very  great 
power.  On  the  other  hand,  we  find  the  idea  persisting  in 
Anaxagoras  that  the  spirit  is  but  a part  or  a fragment  of 
matter.  He  calls  it  “ the  finest  and  purest  of  all  things,”  and 
the  soul  becomes  again  a part  of  that  spiritual  essence  which 
pervades  things,  “now  increasing,  now  diminishing.” 

Although  theoretical  speculation  often  advanced  to  the  doc- 
trine of  the  purely  spiritual  existence  of  the  soul,  it  did  not 
develop,  unaided,  the  conception  which  has  been  a mainstay 
of  dualism,  the  conception  of  immortality.  Neither  could 
the  belief  in  immortality  develop  from  the  soul  cult  of  Greek 
popular  religion.  It  rather  originates  in  mysticism,  which  j 
had  its  bands  of  votaries  among  the  Greeks  and  existed 
side  by  side  with  the  popular  religion,  little  heeded  by  the 
latter.  In  the  Orphic  and  Eleusinian  mysteries  are  heard 
the  echoes  of  the  worldly  wisdom  of  ancient  India  according 
to  which  the  body  is  the  sepulchre  of  the  soul  (acofia  arj/xa 
ijrvxvs)-  The  idea  of  immortality  found  fruitful  soil  in  the 
cult  of  Dionysos  in  which  the  experience  of  ecstasy  furnished 
materials  sufficiently  striking  for  spiritualistic  hypotheses. 
The  convulsive  movements  and  visions  in  the  moment  of 
divine  madness  must  have  suggested  a realm  quite  removed 
from  the  ordinary  realities  of  every-day  life.  The  belief  in 
the  separate  existence  of  the  soul  which  the  experiences  of 
dreams  and  swoons  made  natural  was  thus  confirmed  by  the 


DUALISM  IN  PSYCHOLOGY 


17 


experiences  during  ecstasy.  It  was  an  easy  step  from  this 
point  to  the  doctrine  of  the  dual  existence  of  body  and  soul. 
The  descent  from  the  heights  of  emotional  ecstasy,  to  which 
the  soul  had  been  raised  upon  its  temporary  release  from  the 
body,  to  the  realities  of  the  bodily  life  came  to  be  felt  as  a 
passage  from  one  world  into  another.1 

The  inclusion  of  these  conceptions  within  a theoretical 
world  view  brought  psychological  dualism  to  its  highest 
point  of  development,  a point  reached  in  the  philosophy  of 
Plato.  In  Plato’s  theory  of  ideas  the  soul  is  assigned  a 
sort  of  intermediate  position  between  the  world  of  ideas 
and  the  world  of  matter,  since  the  soul  knows  ideas,  but  is 
itself  bound  to  the  body.  The  fundamental  contradiction 
between  experience  and  the  conceptual  world,  which  runs 
throughout  the  entire  Platonic  system,  is  nowhere  revealed 
more  strikingly  than  in  the  relation  between  body  and  soul. 
They  do  not  constitute  an  organic  unity;  the  body  rather 
appears  as  an  obstacle  hindering  the  soul  in  the  attainment 
of  knowledge  and  of  its  true  life.  The  complete  contrast 
between  the  body  and  the  soul  is,  indeed,  made  the  condition 
of  the  latter’s  immortality.  This  pronounced  dualism  reap- 
pears in  the  empirical  constitution  of  the  soul,  which  con- 
tains two  elements,  a natural  and  a supranatural.  The  con- 
trast between  the  spiritual  and  the  natural  assumes  a more 
striking  form  in  Plato  than  in  Anaxagoras.  Although  the 
connection  between  body  and  soul  becomes  thus  an  insoluble 
riddle,  the  soul  becomes  thereby  an  object  of  supreme  inter- 
est for  speculation.  While  the  knowledge  of  the  empirical 
world  is  for  Heraclitus  a precondition  of  the  knowledge  of  the 
soul,  as  we  have  seen,  the  relation  here  is  completely  reversed : 
the  knowledge  of  the  soul  forms  the  only  avenue  to  the 
knowledge  of  the  world.  Plato  thus  drew  the  pregnant 
consequences  involved  in  the  positions  of  the  Sophists  and 
1 Cf.  Rhode,  Psyche,  II,  1898,  pp.  32  ff. 


18 


HISTORY  OF  PSYCHOLOGY 


Socrates,  and  the  existence  of  psychology  as  an  independent 
science  is  demanded,  even  if  not  actually  assured.  It  was 
impossible  to  carry  dualism  to  a higher  point  of  develop- 
ment than  it  had  attained  in  Plato.  It  is  not  until  the  be- 
ginning of  the  modern  era  in  philosophical  speculation  that  we 
find  a dualism  equally  consistent  and  thoroughgoing,  though 
it  is  now  based  upon  a different  conceptual  formulation. 

A number  of  dualistic  features  appear  also  in  the  psy- 
chology of  Aristotle,  whose  metaphysical  presuppositions  lead 
him  to  make  the  distinction  between  the  active  and  the  pas- 
sive reason.  The  active  reason  is  of  divine  lineage;  separated 
from  the  organic  development  of  human  mental  life,  it  enters 
this  life  from  without  ( dvpadev ).  Such  an  obvious  contra- 
diction Aristotle,  master  that  he  was  of  the  art  of  conceptual 
manipulation,  could  not  allow  to  remain  unrelieved.  His 
metaphysical  theory  that  every  movement  presupposed  three 
conditions,  something  moved,  something  at  once  mover  and 
moved,  and,  finally,  an  unmoved  mover,  suggested  the  solu- 
tion: reason  in  the  human  soul  discharges  the  same  function 
as  the  divine  being  in  the  universe  as  a whole,  that,  namely, 
of  an  unmoved  mover.  Like  the  divine  being,  it  represents 
the  capstone  of  organic  evolution. 

A source  of  dualistic  ideas  similar  to  that  of  the  Dionysian 
cults  is  to  be  found  in  the  Hebrew  representations  of  the  soul. 
The  fusion  of  Hebrew  and  Greek  conceptions  in  Alexandrian- 
Judaic  psychology  is  illustrated  in  the  system  of  Philo,  an 
older  contemporary  of  Jesus,  according  to  whom  the  human 
body  is  composed  of  earthy  elements,  while  the  soul,  which 
traces  its  lineage  to  the  divine  7 rvev/xa,  is  composed  of  ether. 
Platonic  dualism  is  here  seen  to  approach  again  the  Orphic- 
Pythagorean  conceptions,  thus  giving  way  to  a supranatu- 
ralistic  theory  of  soul  life  which  for  a long  period  dominates 
philosophical  speculation. 

It  is  here,  too,  that  a differentiation  is  effected  between  two 


DUALISM  IN  PSYCHOLOGY 


19 


factors  which  had  been  united  in  the  traditional  notion  of 
the  soul,  a physiological  factor,  vital  force,  and  a psycho- 
logical one,  consciousness.  The  distinction  indeed  already 
existed  in  germ  in  Aristotle.  Stoicism,  too,  had  prepared 
the  way  for  the  separation  of  these  elements  by  their  dis- 
tinction between  the  r/yefiovucov  and  the  7 rvev/ia,  thus  creat- 
ing, by  a partial  interpretation  of  the  Aristotelian  “quinta 
essentia,”  the  conception  of  “animal  spirits,”  spiritus  ani- 
mates, a conception  destined  to  a long-lived  existence  in  the 
history  of  psychophysical  speculation.  This  higher  part  of 
the  soul,  which  had  hitherto  been  regarded  as  merely  a 
general  principle  of  rationality,  is  now  designated  as  a 
principle  of  individuality  as  well.  The  threefold  division 
of  the  personality  into  spirit,  soul,  and  body  dominates 
anthropology  from  this  time  on.  While  this  triadic  theory 
obviously  represents  an  attempt  to  connect  psychology  with 
religious  ideas  and  interests,  it  also  suggests  misgivings  on 
the  part  of  those  who  held  the  theory  that  the  complex 
variety  of  psychical  phenomena  may,  after  all,  not  be  capa- 
ble of  derivation  from  a single  unitary  principle.  An  ex- 
haustive exposition  and  proof  of  the  triadic  theory  is  under- 
taken by  Origen  (185-254),  who  ascribes  to  the  soul  the 
powers  of  movement,  representation,  and  desire,  the  spirit 
being  endowed  with  the  power  of  judgment.1 

The  exposition  contained  in  the  metaphysical  system  of 
Plotinus  is  of  a very  similar  character.  Separate  indepen- 
dent and  substantial  souls  owe  their  existence  to  the  world 
soul.  The  incarnation  of  the  soul  within  the  body  is  to  be 
explained  by  the  fall  of  the  soul  from  a previous  state  of 
blessedness.  The  relation  of  the  soul  to  the  body  is  com- 
pared with  that  between  light  and  air.  It  is  said  to  be 
“everywhere  present  without  surrendering  its  identity,  pen- 
etrating everything  without  mixing  with  it.” 

1 De  princ.,  Ill,  1-5. 


20 


HISTORY  OF  PSYCHOLOGY 


The  influence  upon  psychology  of  the  religious  mysticism 
of  the  Neo-Platonists  after  Plotinus  becomes  more  pro- 
nounced as  time  goes  on.  The  Neo-Platonic  definition  of 
the  soul  given  by  Porphyry,  ovaia  apeye0r]<;  avXos  afydapTOs 
iv  fc or)  7 rap  eavTrj ? e^ovarj  to  %rjv  ice/CTT) pevrj  to  eivai}  is  widely 
followed  by  the  Greek  Church  Fathers.  Prominent  among 
the  amalgamations  of  Christian  and  Neo-Platonic  ideas  are 
the  teachings,  based  upon  the  system  of  Plato,  of  Gregory 
ofNyssa  (331-394).  He  considers  the  soul  as  an  incorporeal, 
independent  substance  which  permeates  the  body.  The  lat- 
ter phrase,  however,  is  not  to  be  taken  in  a spatial  sense;  the 
relation  between  soul  and  body  is  much  like  that  between 
light  and  air. 

More  convincing  proofs  of  the  incorporeal  nature  of  the 
soul  are  offered  by  Augustine  (354-430).  The  idea  that  the 
knowledge  of  a thing  implies  an  ontological  affinity  between 
the  knower  and  the  thing  known,  and  that,  consequently, 
that  which  knows  the  incorporeal  must  itself  be  incorporeal, 
is  reminiscent  of  Plato.  More  important  is  the  purely  psy- 
chological argument  that  the  soul,  since  it  is  the  experiencing 
subject,  cannot  be  itself  an  object  of  observation  and  cannot, 
therefore,  have  material  properties.  The  soul  has  an  imme- 
diate knowledge  of  itself  in  self-consciousness.  The  problem 
of  the  relation  between  soul  and  body  Augustine  seeks  to 
make  intelligible  in  a manner  characteristic  of  his  time. 
The  reigning  dogma  of  soul  substance  prevents  him  from 
advancing  to  a monistic  position  and  leads  him  to  assert 
that  the  combination  in  man  of  body  and  soul  results  in  a 
third  substance,  the  exact  nature  of  the  relation  between 
these  substances,  however,  remaining  unfathomable.  A 
clear  expression  of  the  tendencies  of  later  Patristic  psy- 
chology is  found  in  the  teachings  of  Nemesius,  bishop  of 
Emesa  in  Phoenicia,  who  wrote  between  400  and  450.  Tak- 
ing his  stand  against  both  materialism  and  the  Aristotelian 


DUALISM  IN  PSYCHOLOGY 


21 


doctrine  of  the  soul  as  the  entelechy  of  the  body,  he  defends 
an  outspoken  dualism  of  body  and  soul,  contenting  himself 
with  the  definition  of  the  latter  as  an  incorporeal,  inde- 
pendently existing  substance. 

The  psychology  of  Scholasticism,  too,  is  largely  dominated 
by  dualistic  conceptions.  The  early  Scholastics,  Alcuin,  Isaac 
of  Stella,  and  Hugo  of  Saint  Victor,  base  their  ideas  upon 
the  Augustinian-Platonic  system.  With  the  rehabilitation 
of  Aristotelianism  in  the  thirteenth  century  this  develop- 
ment is  for  a time  interrupted,  but  the  fundamental  idea  of 
spiritualism  soon  succumbs  again  to  dualism,  which  received 
powerful  support  from  its  affiliation  with  current  religious 
convictions.  The  Arabian  philosophers  also  assisted  the 
cause  of  dualism  by  making  the  necessary  reinterpretations 
of  the  distinction  between  the  active  and  the  passive  reason. 
The  authority  of  Aristotle  served  also  to  protect  partly  the 
pneuma  doctrine  which,  originally  growing  out  of  hylozoistic 
ideas,  was  now  employed  to  explain  the  connection  between 
soul  and  body.  Pneuma  became  a sort  of  intermediate  agent, 
so  that  the  main  outlines  of  the  triadic  philosophy,  with  its 
division  of  spirit,  soul,  and  body,  were  again  restored. 

A naturalistic  interpretation  of  Aristotelian  doctrines  oc- 
casionally bordering  upon  pantheism  was  given  by  Averroes 
(1126-98). 1 The  soul  is  distinguished  both  from  the  body 
and  from  the  impersonal  intellect.  The  aim  of  intellectual 
knowledge  as  it  develops  is  the  comprehension  by  the  uni- 
versal intellect  of  its  own  activity  and  life  within  the  indi- 
vidual, a process  which  Averroes  describes  as  the  attainment 
by  the  intellect  of  abstract  ideas.2  And  since  forms  emerge 
from  matter  of  necessity,  in  virtue  of  the  principle  of  move- 
ment inherent  in  matter  from  eternity,  the  development  of 

1 Cf.  Siebeck,  Archiv  f.  Gesch.  d.  Phil.,  II,  pp.  516  ff. 

2 “ Ascendit  ille  intellectus  in  actu  ad  assimilationem  rerum  abstrac- 
tarum  et  intelleget  suum  esse,  quod  est  actu  intellectus.”  De  an.  beat., 
66  A. 


22 


HISTORY  OF  PSYCHOLOGY 


the  spiritual  principle  is  a process  which  is  both  natural  and 
necessary. 

It  is  true  that  Thomas  Aquinas  (1224-75),  standing  at  the 
very  summit  of  Scholasticism,  turned  away  from  Platonic 
dualism  and  accepted  the  Aristotelian  conception  of  the  soul. 
The  dogma  of  the  church,  however,  demanded  an  adapta- 
tion of  the  Aristotelian  distinctions  so  as  to  bring  them  into 
harmony  with  the  reigning  system  of  theoSgical  dualism. 
He  accordingly  made  the  distinction  between  subsistent  and 
inherent  forms  and  attributed  to  the  former  an  existence  in- 
dependent of  matter.  The  comment  often  made  upon  the 
philosophy  of  this  period,  namely,  that  it  is  no  more  and  no 
less  scientific  than  the  literary  sources  upon  which  it  drew, 
applies,  on  the  whole,  to  psychology  as  well,  whose  affiliation 
with  philosophy  was  at  this  period  constant  and  intimate. 

In  the  period  immediately  preceding  modern  philosophy 
dualistic  theories  underwent  few  modifications.  This  ap- 
plies, for  instance,  to  the  Marburg  school,  known  to  us 
through  the  Psychologia  of  Rudolf  Gockel,  published  in 
1590.1  Modern  dualism  originates  with  Descartes  (1596- 
1650)  where  it  is  based  upon  new  conceptual  presuppositions. 
Descartes  did  not,  indeed,  succeed  in  liberating  himself  com- 
pletely from  the  scholastic  tradition.  Still,  his  thinking  was 
dominated  by  the  new  scientific  spirit  of  the  time,  with  the 
result  that  the  distinction  between  matter  and  spirit,  which 
had  hitherto  been  regarded  as  merely  one  of  degree,  com- 
pleted itself  in  his  philosophy  in  the  entire  separation  of  the 
two  spheres  in  question.  Descartes  thus  for  the  first  time 
assigned  to  the  physical  and  the  mental  sciences  their  dis- 
tinct subject-matter:  to  the  former  extended  substance,  to 
the  latter  conscious  substance. 

There  is  probably  no  other  distinction  in  the  history  of 

1 Casmann  defines  man  as  “ genuinaj  naturae  mundanse:  spiritualis  et 
corporea  in  unum  hyphistamenon  unite  participes  essentia;.” 


DUALISM  IN  PSYCHOLOGY 


23 


metaphysical  psychology  which  has  been  as  momentous  as 
this.  The  conceptions  and  categories  of  the  older  systems 
of  philosophy  are  often  so  ambiguous  in  character  that  it  is 
impossible  to  say  whether  they  are  physical  or  psychologi- 
cal. They  seem  to  fall  somewhere  between.  Even  where  the 
antithesis  between  the  two  realms  is  made  explicit,  as  in 
Plato,  it  tends  to  pass  over  into  the  antithesis  between  the 
good  and  the  bad  or  between  the  true  and  the  false.  The 
transformation  which  occurred  is  well-nigh  impossible  of 
vital  apprehension  to-day,  for  the  Cartesian  distinction  still 
coincides  with  the  concepts  in  accordance  with  which  naive 
thought  interprets  the  whole  of  our  experience.  With  the 
Cartesian  substitution  of  a pure  dualism  of  substances  for 
the  Platonic  dualism  of  values  the  problem  of  the  relation  of 
mind  and  body  was  raised  into  greater  prominence  than  ever 
before.  The  attempts  to  solve  this  problem  were  of  first- 
rate  influence  in  carrying  psychology  beyond  the  dualistic 
hypothesis.  To  be  sure,  dualistic  ideas  come  into  promi- 
nence again  with  the  return  to  the  great  metaphysical  sys- 
tems of  the  seventeenth  century,  especially  in  the  popular 
philosophy  of  the  Enlightenment.  Indeed,  the  Cartesian 
dualism  became  the  generally  accepted  view-point  of  popular 
thought.  As  a metaphysical  tendency,  however,  it  hence- 
forth assumes  a subordinate  rank.  And  although  we  find 
writers  even  in  the  nineteenth  century  who  espouse  dualism, 
like  Krause,  for  example,1  they  do  not  do  so  without  exhib- 
iting monistic  tendencies. 

With  the  exception  of  the  innovation  of  Descartes  which 
influenced  every  subsequent  psychological  tendency,2  the 
development  of  dualism  was  fairly  consistent  and  uniform. 
In  this  respect  it  resembles  the  earlier  forms  of  empirical 
psychology,  to  be  described  later,  especially  faculty  psy- 

1 Vorlesungen  uber  die  psychische  Anthropologie,  1836. 

2 Cf.  below,  Chapter  VI,  1 ( b ). 


24 


HISTORY  OF  PSYCHOLOGY 


chology.  The  reason  for  this  lies  in  the  fact  that  dualism 
never  undertakes  any  genuine  interpretation  of  the  phenom- 
ena of  experience.  It  is  only  with  the  progress  of  sophisti- 
cation that  the  wealth  of  contrasts  shown  by  monistic  ten- 
dencies becomes  possible. 


CHAPTER  II 


MONISM  IN  PSYCHOLOGY 

Monism  in  psychology  can  either  grow  out  of  the  problems 
raised  by  dualism  or  it  can  from  the  outset  treat  psychical 
and  bodily  phenomena  as  equivalent.  In  the  former  case, 
the  point  of  departure  is  the  problem  of  the  mutual  relation 
of  body  and  mind;  in  the  latter,  the  common  characteristics 
of  bodily  and  mental  phenomena  become  the  starting-point. 
Speaking  generally,  the  effort  to  identify  the  soul,  taken  as 
an  independent  reality,  with  the  body,  leads  to  the  primacy 
of  the  former  and  thus  to  spiritualistic  psychology.  On  the 
other  hand,  the  identification  of  bodily  and  psychical  proc- 
esses tends  to  make  the  physical  world  appear  as  the  real 
world,  and  the  result  is  materialistic  psychology.  It  hap- 
pens, accordingly,  that  in  the  history  of  psychology  spiritu- 
alistic tendencies  follow  in  the  wake  of  a pronounced  du- 
alism, while  materialistic  psychology  grows  out  of  natural 
science  when  carried  on  independently  of  metaphysical  pre- 
suppositions and  influences.  But  the  relation  is  sometimes 
reversed,  with  the  result  that  one  finds  very  diverse  tenden- 
cies combined  in  a given  form  of  spiritualistic  or  material- 
istic psychology. 

Between  these  two  types  stands  pure  monism,  such  as  one 
finds  in  Spinoza,  for  example,  which  co-ordinates  completely 
the  physical  and  the  psychical  aspects  of  reality.  Since  this 
theory,  however,  fails  to  take  account  of  the  empirical  con- 
nections existing  among  the  contents  of  consciousness,  it  can 
hardly  be  said  to  constitute  a separate  branch  of  meta- 
physical psychology,  although  it  bears  close  relations  to  ef- 

25 


26 


HISTORY  OF  PSYCHOLOGY 


forts  to  rid  a given  system  of  empirical  psychology  of  con- 
tradictions and  thus  to  bring  it  to  a definitive  conclusion. 
Within  the  science  of  psychology  itself  the  principle  of  so- 
called  psychophysical  parallelism  has  been  reduced  to  a 
heuristic  principle,  a process  which  has  been  repeated  in  the 
case  of  metaphysical  principles  of  a number  of  other  sciences, 
the  principle  of  finalism,  for  example,  in  biology. 

i . Spiritualism 

Spiritualism  in  psychology  is  the  result  of  the  gradual 
development  of  the  concept  of  spirit  and  of  the  sharpening 
of  the  contrast  between  spirit  and  matter.  A number  of 
spiritualistic  features  are  found  as  early  in  the  history  of 
psychology  as  Anaxagoras,  who  describes  spirit  as  something 
simple  and  unmixed;  but  his  definitions  are  not  free  from 
materialistic  implications.1  It  is  not  until  Aristotle  (384- 
322),  the  thinker  who  might  be  said  to  have  originated 
psychology  as  an  independent  science  with  definitely  fixed 
boundaries,  that  the  magic  word  expressing  the  really  inex- 
pressible nature  of  the  soul  was  spoken.  The  soul  is  to  the 
body  what  form  is  to  matter;  it  is  that  which  makes  of  the 
body  a living  being,  and  which  through  its  activity  completes 
the  body,  by  leading  it  to  its  true  goal.  This  is  the  meaning 
of  that  noteworthy  definition  of  the  soul  as  the  entelechy  of 
the  living  body : eartv  ovv  ivr eXe^eia  rj  rrpcorrj  era)  paros 

<f>vcriKov  £ corjv  eyot>TO?  Bvvap,ei.  In  this  conception  of  the 
soul  are  contained  the  initial  suggestions  which  psychology 
has  not  availed  itself  of  until  the  most  recent  times.  In 
Aristotle’s  psychology  the  soul  is  no  longer  a substance,  but 
an  activity,  a formative  principle.  The  most  important 
conception  of  spiritualistic  psychology  comes  here  to  its  full- 
est expression,  although  Aristotle,  influenced  by  his  meta- 

1 Cf.  above,  p.  16. 


MONISM  IN  PSYCHOLOGY 


27 


physics,  again  lapses  into  dualism.1  In  spite  of  repeated  at- 
tempts on  the  part  of  Neo-Platonism  to  construct  a monistic 
psychology,  spiritualism  remains  a subordinate  type  for  a 
considerable  period.  It  is  revived  again  in  the  metaphysical 
systems  of  modern  philosophy,  reaching  its  highest  develop- 
ment in  Leibniz  (1646-1716),  the  Aristotle,  as  he  has  been 
called,  of  modern  times. 

The  psychology  of  Leibniz  is  based  upon  the  doctrine  of 
monads,  a wholly  metaphysical  conception.  Inasmuch  as 
the  soul  is  the  only  part  of  reality  which  we  immediately 
know,  we  must  interpret  the  rest  of  reality  in  analogy  with 
it.  All  reality  is,  therefore,  psychical  in  character.  It  is 
composed  of  monads  of  varying  degrees  of  development  ar- 
ranged in  a hierarchy  whose  order  is  determined  by  the 
particular  grade  of  development  reached  by  the  monads 
composing  it.  On  the  lowest  plane  are  found  simple  mon- 
ads, whose  psychical  condition  resembles  our  own  in  a state 
of  drowsiness  or  swoon.  Animal  souls  are  endowed  with 
memory.  The  human  soul,  finally,  participates  in  the  high- 
est forms  of  experience  through  its  knowledge  of  necessary 
truths.  Since  all  the  grades  of  consciousness  are  repre- 
sented in  the  monad  constituting  the  human  soul,  the  meta- 
physical conception  in  question,  although  confining  itself  to 
cognitive  experiences,  was  not  without  significance  for  the 
interpretation  of  the  empirical  data  of  consciousness.2 

The  purest  form  of  spiritualism  ever  achieved,  that  of 
Berkeley  (1685-1753),  arose  out  of  different  antecedents. 
The  starting-point  of  Berkeley’s  system,  it  is  true,  was  the 
empirical  psychology  of  Locke,  since  he  characterized  all 
experiences  as  forms  of  self-observation.  But  his  interpre- 
tation of  sense-perception  as  the  lowest  form  of  self -observa- 
tion already  carries  him  beyond  the  bounds  of  experience. 

1 Cf.  above,  p.  18. 

s Cf.  below,  Chapter  VI,  2 (a). 


28 


HISTORY  OF  PSYCHOLOGY 


Once  thoroughly  launched  upon  metaphysics,  Berkeley  finds 
nothing  but  souls  and  their  experiences.  The  soul  is  a sim- 
ple, indivisible,  active  being  which,  in  its  capacity  to  per- 
ceive ideas,  is  called  intelligence;  in  its  capacity  to  produce 
them,  will.  The  peculiarity  of  the  subject  of  inner  experi- 
ence is  suggested  by  the  observation  that  we  can  form  only 
a concept,  not  an  idea,  of  spirit;  nevertheless,  the  definition 
of  spirit  here  proposed  carries  us  far  beyond  the  bounds  of 
science  into  metaphysics. 

The  spiritualistic  psychology  which  nourished  itself  on  the 
Leibnizian  ideas  tended  always  to  lapse  into  vulgar  dualism. 
After  Kant  had  dealt  the  death-blow  to  this  species  of  psy- 
chologizing, as  well  as  to  the  more  traditional  type  of  ration- 
alism, psychology  passed  under  the  sway  of  the  Romantic 
philosophy.  A related  form  of  spiritualism  is  found  in 
France  after  the  Revolution.  Cabanis  (1757-1808)  had,  in- 
deed, sought  to  explain  the  relations  between  physiological 
and  psychological  processes  in  his  principal  work,  Les  rap- 
ports du  physique  et  du  moral  de  I’homme  (1798-9  and, 
separately,  1802),  but  he  assumed  with  Leibniz  a number 
of  subordinate  minds  in  addition  to  the  central  mind,  even- 
tually adopting  a form  of  pantheism  not  unlike  that  of  an- 
cient Stoicism. 

A complete  contrast  to  sensualism  of  the  type  found  in 
Condillac  is  encountered  in  Maine  de  Biran  (1766-1824),  who 
has  done  much  for  the  revival  of  psychology  in  France.  In 
his  Essai  sur  les  fondements  de  la  Psychologie  he  opposes 
equally  the  point  of  view  of  the  metaphysicians  who  treat 
the  soul  as  an  absolute  being  and  that  of  pure  empiricists 
who  recognize  in  the  mental  life  only  sensations  and  connec- 
tions among  sensations.  Reflection  on  our  inner  life  forces 
us  to  recognize  conation  or  wilful  effort  as  the  primary  fact 
of  consciousness.  Will  and  resistance  are  inseparable  ex- 
periences: it  is  through  resistance  that  the  self  becomes 


MONISM  IN  PSYCHOLOGY 


29 


aware  that  it  is  limited.  Other  deductions  of  Maine  de 
Biran  remind  one  of  the  interpretations  of  consciousness  in 
German  Romanticism.  A characteristic  doctrine  is  that 
of  inner  space.  This  is  the  immediate  seat  of  the  ego  and 
is  formed  by  the  various  points  of  resistance  which  the  will 
encounters  in  the  various  organs. 

The  Leibnizian  tradition  is  continued  by  Herbart  (1776— 
1831),  who  himself  acknowledged  Leibniz  as  his  precursor. 
Herbart,  too,  is  not  exempt  from  the  influence  of  the  dia- 
lectic of  Romanticism  in  so  far  as  the  problem  of  psychology 
arises  only  as  a result  of  the  contradictions  contained  within 
the  concept  of  spirit.  In  the  fact  of  self-consciousness  is 
contained,  according  to  Herbart,  the  identity  of  being  and 
knowledge,  of  the  subject  and  object  of  consciousness, 
without  being  differentiated  within  it,  however,  by  thought. 
Thus  psychology  confronts  a metaphysical  problem  at  the 
very  outset  and  it  emerges  from  its  attempts  to  solve  this 
problem  as  a mechanics  of  ideas.  On  account  of  the  contra- 
dictions among  the  empirical  concepts  to  which  experience 
gives  rise,  the  latter  does  not  even  furnish  us  with  phenomena 
from  which  the  nature  of  reality  might  be  inferred.  It  gives 
us  nothing  but  semblance,  and  this  semblance  it  is  the  busi- 
ness of  metaphysics  to  dissipate.  With  this  object  in  mind, 
Herbart  resorts  to  the  Leibnizian  monadology.  He  defines 
even  more  sharply  the  concept  of  the  individual,  simple 
being  of  “the  real.”  Out  of  the  disturbances  and  the  ten- 
dencies to  self-preservation  or  persistence  of  these  reals  he 
deduced  both  the  phenomena  of  the  outer  world  and  the 
processes  of  consciousness.  The  latter  consist  entirely  in 
the  movements  of  ideas.  The  whole  of  reality  is  thus  dis- 
solved, as  if  by  an  act  of  force,  into  reals.  The  physical  and 
psychical  represent  merely  different  stages  in  the  competi- 
tive action,  the  disturbance  and  self-preservation,  of  simple 
elements. 


30 


HISTORY  OF  PSYCHOLOGY 


Aside  from  this  main  line  of  the  development  of  spiritual- 
ism which  has  persisted  in  its  Herbartian  form  up  to  very- 
recent  times,  other  spiritualistic  motives  have  made  them- 
selves felt  in  the  nineteenth  century,  especially  in  connection 
with  the  school  of  Schelling.  The  Aristotelian  definition  of 
the  soul  reappears  in  the  Vorlesungen  iiber  Psychologie 
(1831)  by  C.  G.  Carus,  who  again  defines  it  as  the  principle 
of  life.  Fantastic  analogies  between  body  and  soul,  between 
organs  and  their  functions,  are  met  with'  in  a number  of  psy- 
chologists representing  similar  tendencies,  Schubert,  Fischer, 
Burdach,  and  Heinroth,  whose  names  have  now  passed  into 
oblivion.  This  form  of  spiritualism  received  its  most  ex- 
haustive treatment  at  the  hands  of  J.  H.  Fichte  (1797-1879), 
who  combined  a strong  theological  tendency  with  the  most 
fanciful  psychological  hypotheses. 

Much  more  congenial  is  the  mature  form  of  spiritualism 
which  serves  as  the  background  of  the  empirical  psychology 
of  one  of  the  most  important  psychologists  of  the  nineteenth 
century,  Hermann  Lotze  (1817-81),  the  successor  of  Her- 
bart  at  the  University  of  Gottingen.  Lotze’s  thought  is 
firmly  based  upon  natural  science,  and  he  recognizes  fully  the 
dependence  of  mental  states  upon  bodily  condition.  Never- 
theless, the  ultimate  ground  of  reality  is  for  him  spiritual. 
“Thus  we  are  led  back,”  he  writes,  “to  a psychophysical 
mechanism  within  which  all  interactions  occur  among  homo- 
geneous elements.  This  does  not  mean  that  we  reduce 
mind  to  terms  of  matter,  as  is  done  by  materialism,  but 
rather  that  we  interpret  matter  in  terms  of  mind,  or  of  some 
substance  essentially  akin  to  mind.”  1 

Within  the  movement  of  spiritualism  itself  several  sharply 
contrasted  tendencies  have  lately  made  themselves  felt.  In 
contradiction  to  the  fundamental  metaphysical  principle  that 
the  soul  is  a spiritual  substance  and  the  empirical  principle 
1 Medicinische  Psychologie,  1852,  p.  80. 


MONISM  IN  PSYCHOLOGY 


31 


that  the  intellectual  processes  furnish  the  foundation  for  all 
other  mental  processes,  the  claims  are  advanced,  first,  that 
the  immediately  experienced  actualities  of  the  mental  life  are 
themselves  the  ultimate  reality  of  that  life,  and,  second,  that 
the  phenomena  of  volition  represent  the  fundamental  traits 
of  mental  life  as  a whole.  Thus  arises  the  distinction  be- 
tween substantialism  and  actualism,  on  the  one  hand,  and 
between  intellectualism  and  voluntarism,  on  the  other,  these 
constituting  the  metaphysical  border  problems  of  contem- 
porary psychology.  Anticipated  by  Hume  and  Kant,  who 
had  subjected  the  notion  of  spiritual  substance  to  a vigorous 
criticism,  actualism  is  represented  at  the  present  day  mainly 
by  Wundt  and  Paulsen,  who  also  champion  a pronounced 
voluntarism  as  against  various  forms  of  intellectualism.  The 
controversy  between  substantialism  and  actualism  turned 
mainly  upon  the  metaphysical  question  whether  the  relation 
between  the  substantial  beare?  of  qualities  and  the  qualities 
or  phenomena  themselves  was  thinkable.  As  was  to  be 
expected,  the  influence  of  these  considerations  upon  empirical 
psychology  has  not  been  very  great,  as  can  be  seen  by  com- 
paring the  theories,  say,  of  Lipps  and  Wundt,  the  former  of 
whom  showed  on  the  whole  a tendency  toward  substantial- 
ism. 

Of  more  empirical  significance  is  the  controversy  between 
intellectualism  and  voluntarism.  The  latter  has  antece- 
dents in  the  history  of  psychology  in  various  theories  of  the 
will  which  go  back  to  Duns  Scotus,  or  to  the  end  of  the 
twelfth  century.1  A distinction,  must,  of  course,  be  made 
between  metaphysical  voluntarism,  such  as  we  associate  with 
the  name  of  Schopenhauer,  and  psychological  voluntarism, 
which  regards  the  empirical  process  of  volition,  with  its 
affective,  sensational,  and  ideational  constituents,  as  the  type 
of  consciousness  in  general.  It  is  just  in  the  composite 
1 Cf.  Chapter  XII,  2,  below. 


32 


HISTORY  OF  PSYCHOLOGY 


character  of  the  volitional  process  that  its  typical  signifi- 
cance lies.1  This  principle,  however,  which  was  originally 
meant  to  be  merely  a methodological  principle,  tends  very 
readily  to  become  transformed  into  the  dogma  of  the  meta- 
physical priority  of  volition. 

If  we  review  from  this  point  the  development  of  spiritual- 
istic psychology  we  shall  recognize  the  tendency  to  shift  the 
problem  of  spiritualism  to  the  realm  of  the  border  problems 
of  psychology.  The  various  tendencies  of  spiritualism,  in  so 
far  as  they  have  relevance  for  psychology,  meanwhile  exhibit 
a noticeable  similarity  for  a considerable  period,  since,  while 
extending  the  boundaries  of  the  psychical,  they  do  not  re- 
sort to  heterogeneous  principles  of  explanation,  as  material- 
ism so  often  does. 


2.  Materialism  in  Psychology 

Materialistic  psychology  divides  into  three  main  forms 
according  to  the  relation  asserted  to  exist  between  mental 
and  physical  processes.  In  the  most  naive  form  of  this  doc- 
trine the  soul  is  treated  as  a special  kind  of  substance  which 
penetrates  the  body,  or  else  it  is  outrightly  identified  with 
some  part  of  the  body,  usually  the  brain.  Since  this  form 
resolves  the  soul  into  atoms  similar  to  the  atoms  of  physics, 
it  may  be  called  atomistic  materialism.  The  growing  knowl- 
edge of  brain  processes  combined  with  epistemological  con- 
siderations rendered  atomistic  materialism  unsatisfactory 
and  led  to  the  interpretation  of  mental  processes  as  the  effect 
of  brain  processes.  Thus  arose  mechanistic  materialism,  a 
form  which  developed  concomitantly  with  the  mechanistic 
conception  of  nature.  The  third  most  general  form  is  psy- 
chophysical materialism,  according  to  which  mental  processes 
are  functions  of  specific  bodily  processes.  While  atomistic 
1 Cf.  Wundt,  Grundriss  der  Psychologies  § 2,  10a. 


MONISM  IN  PSYCHOLOGY 


33 


materialism  shows  affiliations  with  substantialism  in  psychol- 
ogy, psychophysical  materialism  resembles  actualism,  since 
the  soul  here  consists  simply  in  the  combination  of  elemen- 
tary psychical  processes,  while  mechanistic  materialism  seems 
again  to  represent  an  intermediate  conception.  The  three 
forms  enumerated  also  represent  roughly  the  historical  se- 
quence which  obtains  among  them.  In  any  event,  the  ear- 
liest form  of  materialism  to  appear  in  the  history  of  psy- 
chology is  atomistic  materialism. 

(a)  Atomistic  Materialism  1 

The  antitheses  of  spiritualistic  and  materialistic  meta- 
physics developed  out  of  the  Jiylozoism  of  the  ancient  Io- 
nians,  in  which  the  concepts  of  soul  and  body  were  still  undif- 
ferentiated. The  first  sketch  of  materialistic  metaphysics 
was  drawn  in  outline,  and  with  bold  strokes,  by  Democritus. 
The  atomistic  materialism  of  Democritus  dispenses  entirely 
with  a spiritual  ground  of  becoming.  The  soul  is  composed 
of  a particular  group  of  atoms,  of  tenuous  structure,  smooth 
and  round,  like  those  of  fire.  These  atoms  are  the  most 
mobile  of  all,  they  penetrate  the  entire  body  and  impart  to 
it  the  principle  of  life.  The  life  of  the  soul  depends  upon 
the  breath,  i.  e.,  upon  the  unrestricted  supply  of  soul  atoms. 
The  reason  the  soul  is  invisible,  Democritus  quite  consis- 
tently adds,  is  that  the  atoms  composing  it  are  too  small  to 
be  seen.  From  these  general  presuppositions  Democritus 
deduces,  with  admirable  attention  to  logical  sequence,  the 
various  empirical  phenomena  of  mental  life. 

Although  the  system  of  Diogenes  of  Apollonia  does  not 
correspond  to  the  atomism  of  Democritus  in  detail,  it  is, 

1 For  the  material  which  follows  the  writer  is  in  part  indebted  to 
F.  A.  Lange’s  Geschichte  des  Materialismus,  which  is  still  the  most  in- 
structive treatment  of  the  problems  of  materialistic  psychology  that  we 
have.  [English  translation  by  E.  C.  Thomas,  London,  1878-81.  Trs.] 


34 


HISTORY  OF  PSYCHOLOGY 


nevertheless,  materialistic  in  character.  The  eternal  and 
unlimited  element  is  air,  through  the  condensation  and  rare- 
faction of  which  originate  cold  and  warmth,  the  dry  and 
the  moist.  The  soul  itself  is  only  a special  form  of  air.  A 
decided  tendency  toward  materialism  manifests  itself  in  vari- 
ous branches  of  the  Peripatetic  school.  As  early  as  Dicae- 
archus  of  Messene  we  find  a repetition  of  the  old  formula 
that  the  soul  is  a harmony,  i.  e.,  a proper  proportion  of  the 
four  elements  composing  the  body.  A thoroughgoing  mate- 
rialistic psychology  was  developed  within  the  Peripatetic 
school  by  Strato,  the  physicist,  who  asserted  that  all  mental 
processes  were  modes  of  motion.  Ignoring  the  subtle  con- 
ceptual discriminations  of  his  master,  he  adopted  the  prin- 
ciple of  pneuma,  already  domesticated  in  the  medical  psy- 
chology of  his  day,  as  a special  principle  of  explanation. 
Although  pneuma  was  described  as  warm  air,  which  pene- 
trates the  body  in  respiration,  the  close  relation  of  air  to 
mental  life  could  not  be  lost  sight  of  so  long  as  the  principle 
of  pneuma  served  as  a connecting  link  between  soul  and 
body.  The  conception  of  pneuma  played  a leading  role  in 
the  psychology  of  the  Stoics.  The  less,  however,  they  felt 
it  as  a difficulty  that  the  fiery  vapor  of  which  pneuma  was 
composed  could  be  at  once  mental  and  material,  the  more 
they  departed  from  the  fundamental  ideas  underlying  the 
atomism  of  Democritus. 

The  sublime  materialism  of  EpicUrus  (341-270  B.  C.)  rep- 
resents the  highest  development  to  which  atomistic  material- 
ism attained.  According  to  him,  too,  the  soul  consists  of 
round  and  smooth  atoms  whose  substance,  however,  is  more 
tenuous  than  that  of  the  odor  of  a flower  or  of  ointment. 
The  soul  represents  the  union  of  four  elements,  fire,  air,  a 
vaporous  substance,  and  a fourth  unnamed  element,  the  most 
tenuous  and  mobile  of  all.  These  physical  distinctions  are 
paralleled  by  certain  psychological  distinctions  in  accor- 


MONISM  IN  PSYCHOLOGY 


35 


dance  with  which  spirit  emerges  in  an  analogous  manner  from 
among  the  other  parts  of  the  soul.  So  long  as  it  remains  in- 
tact other  parts  of  the  soul  substance  can  perish  without 
jeopardy  to  life. 

The  materialism  of  Epicurus  and  the  Stoics  passed  over 
into  the  psychological  systems  of  Roman  writers.  The 
pneuma  doctrine  exhibited  a peculiar  vitality  in  this  process, 
surviving  up  to  the  period  of  Patristic  philosophy,  where  we 
meet  with  it  quite  frequently.  Tertullian  (160-222),  from 
whose  unmeasured  polemic  against  Greek  philosophy  the 
work  De  Anima  originated,  adopted  the  materialism  of  Sto- 
icism in  its  crassest  form.  The  soul  is  literally  the  breath 
of  God  ( flatus  dei ');  it  has  the  same  form  as  the  body  and 
is  composed  of  a bright,  vapory  substance  of  great  tenuity. 
Pneuma  is  no  longer  a special  kind  of  substance,  different 
from  the  soul:  it  is  the  soul  itself,  which  emanates  from  the 
paternal  seed  at  the  time  of  birth.  It  has  organs  which  it 
uses  in  thought,  in  dreams,  and  after  death.  It  is  even  visi- 
ble to  the  eye  of  one  in  a state  of  ecstatic  excitement.  The 
same  combination  of  religious  dogmatism  and  extreme  mate- 
rialism is  found  in  Arnobius  of  Sicca,  who  finds  no  difficulty 
in  uniting  the  ideas  of  the  corporeality  of  the  soul  and  its 
immortality.  The  materialism  of  Tertullian,  sanctioned,  as 
it  was,  by  authoritative  belief,  survives  in  a number  of 
Church  Fathers  in  the  self-contradictory  definition  of  the 
soul  given  by  Methodius  of  Tyre  as  a spiritually  discernible 
body  {aw/ia  voepov ),  and  as  late  as  350  A.  D.  Hilary  of 
Poitiers  unhesitatingly  taught  the  doctrine  of  the  soul’s 
corporeality.  Materialism  disappears  in  the  Scholastic  phi- 
losophy, only  to  be  revived  in  the  seventeenth  century  un- 
der the  influence  of  natural  science  and  of  a sensualistic 
theory  of  knowledge.  The  physician  David  Sennert  (1572- 
1637),  who  rehabilitated  physical  atomism  in  Germany, 
thought  it  possible  that  the  soul  could  exist  in  the  atoms 


36 


HISTORY  OF  PSYCHOLOGY 


composing  living  bodies,  and  held  that  seeds  were  atoms 
endowed  with  latent  consciousness.  It  is  upon  a similar  idea 
of  animated  atoms  that  Fortuninus  Licetus  (1577-1657)  is 
said  to  have  based  his  theory  of  spontaneous  generation. 
The  tendency  of  atomistic  materialism,  however,  was  to 
pass  over  into  one  of  the  other  types  already  mentioned: 
mechanistic  materialism  or  psychophysical  materialism. 

(6)  Mechanistic  Materialism 

The  philosophy  of  the  Renaissance  broke  with  the  tradi- 
tion of  Scholasticism  without  developing  any  marked  ten- 
dency toward  materialism.  The  nearest  approach  to  mate- 
rialism among  the  leading  thinkers  in  the  early  period  of 
modern  philosophy  is  perhaps  made  by  Bacon.  Bacon’s 
psychological  views  were  extensively  influenced  by  the  con- 
ception of  animal  spirits  ( spiritus  aniviales),  the  presence 
or  absence  of  which  distinguishes,  according  to  him,  living 
from  inanimate  bodies.  Bacon  goes  so  far  as  to  surmise 
that  sensation  itself  consists  in  nothing  but  the  movement 
of  animal  spirits.  The  doctrine  of  animal  spirits  is  the  com- 
mon element  among  many  otherwise  diverging  tendencies 
in  the  psychology  of  this  period.  Descartes,  too,  utilized 
the  hypothesis  for  the  explanation  of  the  manner  in  which 
external  impressions  can  affect  the  soul.  His  belief  was  that 
animal  spirits  existed  in  the  shape  of  highly  mobile  blood 
particles  which,  after  being  thinned  by  the  warmth  of  the 
heart,  flow  to  the  brain  in  order  there  to  form  the  mediating 
link  between  brain  impressions  and  the  pineal  gland.1 

The  real  founders  of  modern  materialism  are  Gassendi 
and  Hobbes.  It  is  the  lasting  merit  of  Gassendi  (1592- 
1655)  that  he  revived  the  most  finished  system  of  material- 
ism of  antiquity,  that  of  Epicurus.  Preoccupied  as  he  was, 
1 Les  passions  de  V&me,  I,  10. 


MONISM  IN  PSYCHOLOGY 


37 


however,  with  the  external  world,  he  purposely  abandoned 
the  problems  of  psychology  with  the  confession  that  it  was 
impossible  to  explain  how  sensation  can  arise  out  of  me- 
chanical antecedents.1  The  hypothesis  that  germ  particles 
endowed  with  the  principle  of  life  have  existed  from  eter- 
nity seems  to  him  to  offer  a way  of  escape  from  the  diffi- 
culty. While  he  attributes  sensation  to  the  material  soul, 
which  is  composed  of  atoms,  he  reserves  thought  for  the 
rational,  immaterial  soul,  which  is  created  separately  for 
each  individual  by  the  Creator.  Thus  Gassendi  abandons 
that  consistency  of  form  which  made  the  system  of  Democ- 
ritus so  admirable  a theoretic  structure. 

Modern  mechanistic  materialism  was  founded  by  Hobbes 
(1588-1671),  who  took  up  the  very  problem  which  Gassendi 
had  given  up  as  hopeless.  Even  in  the  face  of  this  problem 
Hobbes  is  not  wdlling  to  abandon  the  fundamental  principle 
that  movement  is  the  sole  reality.  The  movements  of  cor- 
poreariubstances  are  transmitted  to  the  senses,  wThence  they 
pass  to  the  brain  and  from  there  to  the  heart.  Here  the 
movement  is  reflected,  and  the  counter-movement,  proceed- 
ing from  the  heart  to  the  brain  and  thence  to  the  peripheral 
organs,  is  the  sensation.  All  the  other  psychical  phenom- 
ena develop  out  of  the  movement  of  sensation  by  mechan- 
ical processes  of  a similar  sort.  The  soul  is  thus  no  longer 
a particular  kind  of  matter  as  in  ancient  materialism;  it 
has  become  an  effect  of  mechanical  processes.  Moreover, 
Hobbes  does  not  start  with  the  concept  of  the  soul  but  with 
the  elements  of  mental  life.  Here,  too,  the  Jirst  influence  of 
empiricism  makes  itself  felt.  England,  henceforth,  remains 
theMiome  of  materialism.  One  of  the  best-known  literary 
documents  of  the  psychological  materialism  associated  with 
the  free-thought  movement  are  Toland’s  Letters  to  Serena, 

1 Opera,  Florence,  1725,  II  (2)  8,  sect.  Ill,  t.  VI,  c.  3:  “Qui  sensibile 
gigni  ex  insensibilibus  possit.” 


38 


HISTORY  OF  PSYCHOLOGY 


Sophia  Charlotte,  Queen  of  Prussia  (1704),  in  which  thought 
is  described  as  an  accompaniment  of  the  material  processes 
in  the  brain. 

The  type  of  materialism  under  consideration  is  enriched 
by  the  founders  of  associational  psychology,  Hartley  and 
Priestley.  Hartley  (1704-57)  is  the  originator  of  the  vibra- 
tion hypothesis  according  to  which  mental  processes  have 
as  their  physical  counterparts  specific  vibrations  of  brain 
fibres.  He  did  not,  however,  draw  the  materialistic  conse- 
quences of  this  hypothesis,  but  confessed  that  the  analysis 
of  psychical  processes  must  always  yield  psychical  constit- 
uents, and  that  a sensation  which  is  not  capable  of  fur- 
ther analysis  cannot  be  explained  by  movement.  Priestley 
(1733-1804)  developed  these  new  materialistic  presupposi- 
tions into  a rounded  system  of  psychology.  He  sees  a 
proof  for  the  identity  of  brain  and  mind  in  that  uniform  co- 
ordination in  consequence  of  which  all  psychical  phenom- 
ena, among  which  the  associations  of  ideas  form  the  most 
important  role,  are  determined  by  brain  vibrations. 

Without  contributing  to  psychology  any  original  points 
of  view,  mechanistic  materialism,  together  with  all  it  implied, 
passed  over  into  the  systems  of  Lamettrie  and  Holbach. 
At  the  same  time  we  encounter  here  the  transition  to  our 
final  form  of  materialism,  psychophysical  materialism. 


(c)  Psychophysical  Materialism 

This  form  of  materialism  was  introduced  into  psychology 
by  Diderot,  who  held  that  some  material  process  was  in- 
volved in  every  act  of  sensation.  It  is  true  that  in  express- 
ing this  thought  he  was  not  without  forerunners,  and  there 
were  other  writers  of  his  own  period  who  agreed  with  him. 
The  general  background  is  furnished  by  the  metaphysics 
of  Spinoza,  whose  principles  have  influenced  psychology  in 


MONISM  IN  PSYCHOLOGY 


39 


very  diverse  ways.  Maupertuis,  too,  had  written  of  senti- 
ent atoms  in  an  anonymous  piece  published  in  1761,  and  in 
his  Buck  von  der  Natur,  published  in  the  same  year,  he  ap- 
plied the  principle  of  psychophysical  parallelism  throughout 
in  connection  with  the  discussion  of  voluntary  movement. 
While  his  fantastic  system  permitted  of  only  an  occasional 
application  of  this  principle,  Diderot  developed  the  psy- 
chological principles  involved  in  parallelism  with  much 
clearness.  Thus  he  accounted  for  the  unity  of  conscious- 
ness by  the  supposition  that  the  sentient  particles  of  matter 
come  into  immediate  contact  with  each  other.  From  the 
spatial  continuity  of  atoms  follows  the  unity  of  the  mental 
elements  associated  with  them. 

The  form  of  materialism  under  discussion  has  also  influ- 
enced the  most  recent  psychological  movement  in  Germany, 
where  we  find  indications  of  materialistic  ways  of  thinking 
as  early  as  the  beginning  of  the  eighteenth  century.  A 
much-discussed  anonymous  piece,  Brief  wechsel  iiber  die  Seele 
(1713),  which  apparently  originated  under  the  influence  of 
the  English  Enlightenment,  defended  the  view  that  all  sen- 
sations and  ideas  originate  from  movements  of  brain  fibres 
(, fibris  cerebri).  In  the  eighteenth  century,  the  century  of 
the  Enlightenment',  a period  so  memorable  for  the  history 
of  our  science,  materialistic  psychology  was  widely  influ- 
enced by  the  presuppositions,  borrowed  from  association  psy- 
chology, of  the  dependence  of  psychical  processes  upon  brain 
processes.1  A deeper  comprehension  of  the  principle  of  psy- 
chophysical parallelism  is  revealed  in  many  utterances  of 
Kapt,  which  point  to  a pure  monism.  His  criticism  of  ra- 
tional psychology  indeed  involved  a demand  for  a purely 
empirical  psychology,  but  he  admitted  the  possibility,  at  the 
same  time,  of  a solution  of  the  fundamental  metaphysical 
problem  of  psychology.  If  matter  were  a thing  in  itself,  it 
1 Cf.  Chapter  IV,  2,  below. 


40 


HISTORY  OF  PSYCHOLOGY 


would,  as  a composite  reality,  be  absolutely  different  from 
the  soul,  which  is  simple.  But  since  it  is  merely  an  external 
phenomenon,  it  is  possible  to  suppose  that  what  appears  to 
the  physical  senses  as  extended  substance  is  endowed  with 
thought  which  can  be  consciously  apprehended  by  its  own 
inner  sense.  That  which  in  one  relation  is  called  corporeal 
would  in  another  relation  be  conscious.1 

A new  era  in  the  history  of  materialistic  psychology  begins 
as  a reaction  to  the  philosophy  of  Romanticism,  and  develops 
hand  in  hand  with  the  progress  of  natural  science.  The 
most  influential  representatives  of  this  tendency  in  the  lat- 
ter half  of  the  nineteenth  century  were  Moleschott  and  Buch- 
ner. Moleschott’s  view  approaches  equative  materialism, 
which  identifies  brain  and  mind,  while  Buchner  contents 
himself  with  asserting  the  indissoluble  connection  between 
spirit  and  matter.  Just  how  physical  movement  is  trans- 
formed into  consciousness  is  for  him  an  irrelevant  question. 
With  all  the  emphasis  which  one  finds  here  upon  experience, 
there  is  a curious  absence  of  any  genuine  psychological  analy- 
sis. With  a naivete  which  is  nothing  less  than  archaic,  all 
conscious  processes  are  classified  under  the  common  head  of 
“thought.”  Empirical  psychology  can,  of  course,  not  be 
built  upon  such  foundations.  Even  the  most  profound 
thinker  among  these  materialists,  Czolbe  (1819-73),  who 
made  the  exclusion  of  the  supersensible  the  fundamental 
principle  of  his  system,  abandoned  all  pretence  of  empirical 
investigation,  losing  himself  in  a maze  of  hypotheses  con- 
cerning the  sentiency  of  atoms,  and  arriving  at  a sort  of 
world  soul  composed  of  vibrating  atoms  endowed  with  con- 
sciousness. It  is  only  in  the  human  organism  that  they  con- 
solidate sufficiently  to  make  individualized  psychical  life 
possible. 

The  controversy  over  materialism  in  Germany  differed 
1 Kant,  Kritik  der  reinen  Vernunft,  ed.  Rosenkranz,  p.  288. 


MONISM  IN  PSYCHOLOGY 


41 


from  earlier  controversies  mainly  in  the  influence  of  Dar- 
winism. On  the  whole,  psychology  profited  but  little  from 
this  controversy.  In  the  far-ranging  discussion  regarding 
the  nature  of  the  soul  between  Carl  Vogt  and  Rudolph  Wag- 
ner, Virchow  also  took  part.1  The  energy  of  soul  substance 
or  of  psychical  ether,  he  insisted,  must  ultimately  be  sus- 
ceptible of  physical  measurement.  The  controversy  reached 
its  climax  in  the  association  of  natural  scientists  which  con- 
vened in  Munich  in  1877,  where  Haeckel  asserted  that  the 
cell  was  the  basis  of  all  psychical  life.  We  must  assume 
the  existence  of  soul  life  in  the  cell,  and,  in  order  to  carry 
the  matter  to  a logical  conclusion,  attribute  consciousness  to 
atoms.  This  “ Plastidulseele,”  as  it  was  humorously  called, 
was  criticised  with  unsparing  irony  by  Virchow. 

Thus  psychological  materialism  in  this  final  form  either 
dropped  back  into  the  ways  of  thinking  of  older  metaphysical 
systems,  or  else  it  recognized  the  principle  of  psychophys- 
ical parallelism  and  became  a border  problem  of  empirical 
psychology,  as  in  Bastian,  for  example,  in  Germany,  or  in 
Herbert  Spencer,  in  England. 

Materialistic  presuppositions  also  occasionally  developed 
into  specifically  modern  ideas.  A peculiar  form  of  material- 
istic psychology  was  worked  out  by  Jager,2  a Darwinian  zo- 
ologist of  the  old  school,  according  to  whom  psychic  vapors 
radiate  from  the  body  which  affect  the  olfactory  sense,  and 
thus  give  rise  to  love,  family  and  race  solidarity,  etc.,  in  the 
percipient.3  Jager’s  ideas  won  some  recognition,  especially 
among  the  Darwinians,  who  hailed  Jager’s  efforts  as  the  be- 
ginnings of  a chemistry  of  the  soul,  but  they  were  also  sub- 
jected to  much  ridicule.  Jager’s  theories  met  with  some 
favor  outside  of  the  exact  sciences.  Mantegazza,  for  ex- 

1 Ges.  Abh.  z.  vriss.  Med.,  1856,  p.  17. 

2 Jager,  G.,  Die  Entdeckung  der  Seele,  III,  2d  ed.,  1880. 

3 Cf.  Rddl,  Geschichte  der  biologischen  Theorien,  II,  1909,  p.  435. 


42 


HISTORY  OF  PSYCHOLOGY 


ample,  utilized  them  in  his  notorious  work,  Physiology  of 
Love.  They  have  to  some  extent  been  revived  by  J.  Loeb, 
who  attempted  to  construct  a comparative  psychology  upon 
chemistry,  and  who  saw  in  his  theory  of  tropism  the  key  to 
the  elementary  phenomena  of  life.1  The  discussion,  how- 
ever, as  will  be  seen,  has  now  shifted  completely  from  the 
field  of  metaphysics  to  that  of  physiology. 

A comparison  of  the  various  forms  of  materialistic  psy- 
chology shows  that  they  have  developed  in  connection  with 
different  influences.  In  dualistic  psychology,  for  example,  we  \ 
find  a combination  of  popular  ideas  and  religious  demands; 
spiritualistic  psychology  has  been  very  closely  associated  ; 
with  the  great  philosophical  systems;  while,  finally,  material-^ 
istic  psychology  has  always  appeared  concomitantly  with ' 
natural  science.  These  general  influences  have  always  dom- 
inated psychological  reflection;  we  shall  meet  with  them 
again  as  we  seek  to  trace  the  various  tendencies  of  empirical 
psychology. 


Dynamics  of  Living  Matter,  1906. 


II.  EMPIRICAL  PSYCHOLOGY 


CHAPTER  III 

DESCRIPTIVE  PSYCHOLOGY 

Empirical  psychology  can  be  divided  according  to  differ- 
ent points  of  view.  Although  its  various  tendencies  agree 
among  themselves  as  regards  the  proper  point  of  departure 
for  psychological  investigation,  namely,  the  testimony  of 
introspection,  they  differ  from  each  other  partly  as  regards 
the  principles  to  be  employed  in  the  analysis  and  combina- 
tion of  psychical  facts,  partly  as  regards  the  exact  scientific 
goal  which  empirical  psychology  should  set  for  itself.  The 
latter  difference  divides  empirical  psychology  into  two  lead- 
ing types,  descriptive  psychology  and  explanatory  psy- 
chology. To  be  sure,  descriptive  and  explanatory  psychol- 
ogy do  not  represent  contradictory  but  supplementary  points 
of  view.  Nevertheless,  the  preponderance  of  the  one  or 
the  other  method  of  procedure  is  usually  sufficiently  dis- 
tinct to  keep  the  tendencies  separate.  The  conceptual  sep- 
aration of  these  two  points  of  view  has,  of  course,  not  taken 
place  until  comparatively  recently.  Some  psychologists — 
Lipps,  for  example — have  taken  an  extreme  view  of  this 
relation  and  have  declared  the  problem  of  explanatory  as 
distinguished  from  descriptive  psychology  to  be  the  estab- 
lishment of  causal  connection  within  reality,  thus  gaining  a 
basis  or  substructure  for  the  empirical  data  of  consciousness.1 
The  sharp  opposition  of  the  two  tendencies  seen  here  has  de- 
1 Leitfaden  der  Psychologie,  3d  ed.,  1909,  p.  43. 


44 


HISTORY  OF  PSYCHOLOGY 


veloped  out  of  an  earlier  status,  where  the  contrast  was 
not  nearly  so  marked  and  where  the  descriptive  type  of 
psychology  was  on  the  whole  the  predominant  one.  Mean- 
while there  are  various  points  of  contact  between  the  two 
forms  of  psychology  under  consideration.  Thus  what  is 
called  intellectualism  in  psychology  has  often  operated 
against  an  unbiassed  study  of  the  mental  life.  The  ten- 
dency to  intellectualize  the  mental  processes,  to  force  them 
into  a conceptual  system  dominated  by  intellectual  catego- 
ries, has  characterized  descriptive  and  explanatory  psychol- 
ogy throughout.1  Supported,  on  the  one  hand,  by  the  ideas 
current  in  popular  psychology  and,  on  the  other,  by  certain 
metaphysical  presuppositions,  intellectualism  has  made  it- 
self felt  both  in  faculty  psychology  and  in  association  psy- 
chology. 

Descriptive  psychology  was  for  a long  period  dominated 
by  prescientific  conceptions.  This  period  coincides  in  the 
main  with  that  of  faculty  psychology.  Reflection  upon  the 
question  as  to  how  psychical  facts  are  known  led  to  the  psy- 
chology of  the  inner  sense,  which  forms  the  starting-point  for 
a number  of  tendencies  in  the  modern  phenomenology  of 
consciousness. 

i.  Period  of  Prescientific  Concepts:  The  Doctrine  of 
Mental  Faculties 

Perhaps  more  than  any  other  science,  psychology  has  had 
to  face  and  settle  accounts  with  prescientific  conceptions,  such 
as  one  encounters  at  the  threshold  of  every  science.  The 
terms  of  every-day  speech  which  are  used  to  designate  cer- 
tain experiences  are  adopted  uncritically  both  for  purposes 
of  description  and  of  explanation.  But  explanation  must 

1 Cf.  Wundt,  “Logik  u.  Psychologie,”  Zeitschrift  fur  padagogische  Psy- 
chology u.  Hygiene,  1910,  pp.  1 ff. 


DESCRIPTIVE  PSYCHOLOGY 


45 


always  remain  primitive  and  inadequate  so  long  as  the  hasty 
descriptions  of  common  usage  are  substituted  for  the  gen- 
uine analysis  of  the  phenomena  concerned.  Prior  to  every 
form  of  scientific  psychology  the  terms  soul,  reason,  will, 
and  the  like  are  already  in  common  use.  They  serve  the 
purposes  of  classification  about  in  the  same  way  that  the 
terms  light,  sound,  etc.,  serve  to  classify  physical  phenom- 
ena. Such  rude  classifications  are  indispensable  for  purposes 
of  general  orientation,  and  even  scientific  usage  must  begin 
with  them.  While,  however,  popular  physical  classifications 
have  corresponded  fairly  well  to  the  classifications  which 
have  resulted  from  a more  exact  analysis  of  physical  phe- 
nomena, the  needs  which  have  been  of  influence  in  shaping 
the  distinctions  of  popular  psychology  have  not  been  quite 
the  same  as  those  which  influence  scientific  psychology,  so 
that  a considerable  discrepancy  between  the  popular  and 
the  scientific  classifications  was  bound  to  result. 

Most  of  the  concepts  in  question  show  a considerable 
degree  of  generality,  while  appropriate  designations  for  the 
more  specific  groups  of  mental  phenomena,  like  certain 
kinds  of  simple  feelings,  are  wanting  altogether.  It  was  the 
salient  differences  in  complex  experiences  which  first  forced 
themselves  upon  the  introspective  attention.  The  gener- 
ality of  the  concepts  thus  originating  favored  the  tendency 
to  substantialize  them,  a tendency  which  is  traceable  to  the 
earliest  nature  mythologies,  from  which  the  concepts  in 
question  passed  over  into  metaphysical  psychology.  The 
traces  are  also  revealed  in  the  empirical  applications  which 
these  concepts  have  received.  The  need  for  a rational  com- 
prehension of  psychical  facts  prompted  the  appropriation  of 
these  class  designations  and  transformed  them  into  powers 
or  faculties  which  are  supposed  to  produce  the  psychical 
facts  to  be  explained.  The  notion  of  power  is  meanwhile 
still  mythological  in  its  significance.  If  human  volition  con- 


46 


HISTORY  OF  PSYCHOLOGY 


stituted  the  origin  of  the  idea  of  power,  and  if  power  thus 
manifests  itself  in  things  as  the  human  will  manifests  itself 
in  actions,  then  the  transformation  into  faculties,  together 
with  the  personification  implied  in  that,  must  find  its  justi- 
fication in  the  caprice  with  which  psychical  phenomena  mani- 
fest themselves.  Thus  arose  the  concept  of  mental  faculty, 
which,  self-contradictory  as  it  appears,  was  well  adapted  to 
account  for  psychical  experiences  as  these  presented  them- 
selves to  the  primitive  mind. 

Faculty  psychology  originally  stood  in  intimate  relation 
with  the  metaphysical  doctrine  of  the  parts  of  the  soul.  No- 
table beginnings  of  empirical  psychology  were  made  in  the 
faculty  psychology  of  Scholasticism.  The  psychology  of 
the  Renaissance,  developing,  as  it  does,  in  many  directions, 
represents  a transition  to  the  faculty  theories  of  modern 
psychology.  The  various  forms  of  faculty  psychology  are 
meanwhile  principally  distinguishable  on  the  basis  of  histor- 
ical epochs,  a matter  which  is  readily  understood  since  the 
development  of  any  new  point  of  view  would  of  itself  lead 
psychology  beyond  prescientific  conceptions  and  hence  also 
beyond  the  point  of  view  of  faculty  psychology. 


(a)  The  Doctrine  of  the  Parts  of  the  Soul 

j In  its  earliest  form  the  doctrine  of  mental  faculties  is  diffi- 
I cult  to  distinguish  from  the  doctrine  of  the  parts  of  the  soul. 
The  only  thing  possible  for  metaphysical  psychology  was  to 
divide  the  soul  in  accordance  with  existing  verbal  distinc- 
tions. Such  a partition  of  the  soul  could  either  take  place 
upon  the  basis  of  empirical  differences  found  among  differ- 
ent psychical  processes  or  else  a gradation  of  these  processes 
could  be  undertaken.  The  first  principle  of  division  depends, 
from  our  modern  point  of  view,  upon  the  fact  that  certain 
mental  contents  can  be  classed  together  in  virtue  of  the  pos- 


DESCRIPTIVE  PSYCHOLOGY 


47 


sibility  of  passing  from  one  to  another  of  the  contents  within 
a group  by  intermediate  gradations,  whereas  such  a transi- 
tion is  impossible  between  members  of  one  group  and  those 
of  another.  Thus  one  can  pass  from  one  feeling  to  another 
through  intermediate  feelings,  but  one  could  by  no  possi- 
bility pass  from,  say,  a feeling  of  unpleasantness  to  the  sen- 
sation of  blue.  The  second  principle  of  division  depends 
upon  the  observed  fact  that  within  a given  group  of  more  or 
less  complex  processes,  as,  for  example,  cognitive  processes, 
a number  of  different  steps  or  stages  can  be  distinguished. 
Other  classes  of  processes  can  be  marked  off  on  the  basis  of 
their  objects  or  of  their  relation  to  other  mental  processes.1 

The  first-mentioned  and  most  commonly  accepted  ground 
of  division  was  the  one  which  forced  itself  first  upon  the 
attention.  We  meet  it  in  the  Pythagorean  doctrine  of  the 
parts  of  the  soul.  It  was  here  that  Aresas  of  Croton  in- 
vented the  terminology  later  adopted  by  Plato.  The  well- 
known  tripartite  division  of  the  soul  into  reason  (to 
XoyiaTiicov) , will  (to  0v/j.oet.8e;),  and  desire  (to  eTndvixrjrucov) 
were  in  Plato,  of  course,  still  derived  from  the  idea  of  the 
mixture  of  the  soul  with  the  body  in  the  sense  of  his  meta- 
physical psychology.  The  Platonic  division,  however,  is  an 
anticipation  of  the  later  classification  of  psychological  proc- 
esses into  those  of  cognition,  feeling,  and  desire. 

To  these  psychological  distinctions  corresponds  a spa- 
tial separation  of  the  various  parts  of  the  soul,  with  the 
vovs  located  in  the  head,  the  6v fjuk  in  the  breast,  and  the 
emOvfi-qTLKov  in  the  lower  part  of  the  body.  This  locali- 
zation of  the  parts  of  the  soul  was  widely  accepted  in  the 
psychology  of  antiquity.  Even  Democritus,  whose  scien- 
tific attainments  far  exceeded  those  of  his  contemporaries, 
agrees  in  this  respect  with  the  traditional  views,  locating 

1 For  further  particulars  concerning  principles  of  classification  see 
Chapter  VII,  below. 


48 


HISTORY  OF  PSYCHOLOGY 


reflection  in  the  brain,  anger  in  the  heart,  and  desire  in  the 
liver. 

z Plato  apparently  drew  a further  distinction  within  each 
of  the  parts  of  the  three  divisions  of  the  soul.  Each  of  the 
parts  is  characterized  by  a particular  form  of  desire,  the 
highest  by  Eros,  the  characteristic  of  the  (jnX6ao(po<; . 
Each,  too,  is  characterized  by  a particular  kind  of  pleasure 
whose  grade  is  determined  by  the  value  of  the  particular 
part  of  the  soul  to  which  it  belongs.  There  are  also 
suggestions  of  a relation  between  sense-perception  and 
desire  ( hnOv^Tucov ),  and  between  opinion  (8oga)  and 
6v/ioei,8es.  Here  the  second  principle  of  division  makes 
itself  felt  in  so  far  as  different  grades  are  assumed  within 
the  departments  of  cognition,  feeling,  and  desire.  Side  by 
side  with  these  distinctions  is  also  found  the  distinction — 
a direct  outgrowth  of  metaphysical  dualism— between  the 
higher  and  the  lower  parts  of  the  soul,  a division  plainly 
based  upon  the  various  grades  of  conscious  processes  and 
brought  into  harmony  with  the  former  by  the  fact  that  the 
lower  part  of  the  soul  as  sensibility  comprehends  both  desire 
and  feeling. 

The  doctrine  of  the  parts  of  the  soul  is  in  Aristotle  trans- 
formed into  the  doctrine  of  mental  faculties.  Aristotle  lo- 
cated the  soul  in  the  heart,  as  the  centre  of  the  body,  an 
idea  which  for  a long  time  competed  successfully  with 
the  scientific  doctrine  that  the  brain  was  the  seat  of  psychi- 
cal phenomena.  The  latter  doctrine,  already  held  by  the 
physicians  of  ancient  Egypt,  was  eventually  recovered  by 
Herophilus  of  Alexandria  and  Galen.  The  older  spatial 
separation  gave  way  in  Aristotle  to  conceptual  distinctions 
which  are  based  upon  the  successive  stages  of  biological 
development.  Experience  reveals  four  such  stages:  (1) 
growth  and  nutrition  (to  Opeirrucov),  (2)  sensation  and  im- 
agination ( aladrjTiKov  and  fyavTaarucov) , (3)  conation  and 


DESCRIPTIVE  PSYCHOLOGY 


49 


locomotion  (opefCTt/cdv  and  kiv^tucov  /card,  t ov  t ottov),  and 
(4)  thought  (Siavor/Tucov) . Conation,  however,  which  oc- 
casionally is  divided  into  desire  (e7 tlOv^lo),  feeling  (dvpos), 
and  will  (/3ov\T)cn<;),  and  locomotion  are  in  the  main 
subordinated  to  sensation  as  impulse  and  to  thought  as 
will,  so  that  the  scheme  reduces  to  a tripartite  division,  the 
nutritive,  sensitive,  and  rational  soul.  The  plant  possesses 
only  the  first,  the  animal  the  first  and  the  second,  while  man 
possesses  all  three.  The  Platonic  bipartite  division  here 
reasserts  itself,  since  the  two  lower  faculties  present  a com- 
mon antithesis  to  reason  (SiavorjTucdv) . 

Although  the  Aristotelian  system  offers  no  new  distinc- 
tions, it  nevertheless  possesses  two  advantages.  In  the 
first  place,  the  idea  of  the  unity  of  the  soul  is  asserted,  since 
neither  of  the  facidties  mentioned  is  capable  of  operating  in 
independence  of  the  rest.  Secondly,  there  is  a clear  sugges- 
tion of  the  evolutionary  point  of  view.  The  rough  distinc- 
tions proposed  do  not,  of  course,  completely  solve  the  prob- 
lem of  classification;  but  with  the  contention  that  the  higher 
faculties  presuppose  the  lower  is  combined  the  thought 
that  the  human  soul  stands  in  the  same  relation  to  the 
animal  soul  as  the  higher  faculties  stand  to  the  lower,  so 
that  here,  too,  the  unifying  idea  of  evolution  tends  to  bridge 
over  the  dualism  which  would  otherwise  exist. 

It  is  the  latter  idea  especially  which  was  followed  out  in 
Patristic  philosophy.  Dicsearchus  even  refused  to  recognize 
any  longer  the  distinction  between  the  rational  soul  and 
the  sensory  functions.  Diodorus  of  Tyre  supported  him  in 
this,  but  associated  both  functions  with  an  identical  sub- 
stance, ether.  The  Stoics,  indeed,  possessed  in  pneuma  the 
physical  principle  of  unity  of  the  soul  life,  but  they  did  not 
hesitate  to  grant  the  existence,  at  the  same  time,  of  an  in- 
creasing number  of  mental  faculties.  The  Stoics  were,  per- 
haps, the  first  to  recognize  the  five  senses  as  parts  or  facul-. 


50 


HISTORY  OF  PSYCHOLOGY 


ties  of  the  soul,  i.  e.,  of  the  pneuma.  Adding  to  these  the 
power  of  reproduction,  of  speech,  and  of  reason,  there  re- 
sulted a total  of  eight  faculties,  with  the  ruling  faculty,  rea- 
son (r/yeyovucdv) , at  the  head.  In  later  Stoicism  and  in 
the  earlier  developments  of  Neo-Platonism,  psychology 
merely  repeats  the  Platonic  and  Aristotelian  distinctions. 
The  doubtful  comparison  of  the  soul  and  its  faculties  to  a 
house  and  its  inmates  originated  with  Philo. 

Patristic  philosophy,  whose  metaphysical  psychology  un- 
avoidably involved  the  doctrine  of  the  unity  of  the  soul, 
appears  to  have  been  only  slightly  influenced  by  the  faculty 
psychology.  Tertullian  opposed  the  Platonic  division  of  the 
soul  into  parts,  pointing  out  convincingly  that  the  difference 
between  the  higher  and  the  lower  faculties  of  knowledge 
rested  upon  the  nature  of  the  objects  of  knowledge,  the  cog- 
nitive soul  being  equally  active  in  all  cases,  and  he  compared 
the  distribution  of  the  soul  throughout  the  body  to  the  divi- 
sion of  a column  of  air  as  it  passes  into  the  different  pipes 
of  an  organ.  To  be  sure,  the  tripartite  division  of  Aristotle 
reappears  in  Gregory  of  Nyssa,  the  parts  of  the  soul  being 
expressly  designated  as  mental  faculties.  On  the  other  side, 
however,  is  the  great  authority  of  Augustine,  who  insists  | 
upon  the  strict  unity  of  the  soul.  It  is  not  until  the  period  ' 
of  Scholasticism  that  the  Aristotelian  doctrine  of  mental 
faculties  is  again  revived;  here,  however,  it  is  combined  with 
sundry  efforts  at  purely  empirical  investigation,  a fact  which 
differentiates  the  faculty  psychology  of  Scholasticism  from 
all  previous  types. 

(b)  The  Beginnings  of  Empirical  Psychology  in  Scholasticism 

j Scholasticism  seems  often  at  first  sight  to  be  merely  a 
synonym  for  useless  dialectical  controversies.  Nothing  is 
more  improbable,  however,  than  the  belief  that  men’s  desire 


DESCRIPTIVE  PSYCHOLOGY 


51 


for  empirical  knowledge  should  have  remained  latent  for  a 
period  of  history  of  the  extent  of  Scholasticism.  In  the 
absence  of  an  interest  in  external  nature,  the  knowledge  of 
which,  at  least  during  the  Platonic  period  of  Scholasticism, 
was  largely  dependent  upon  the  fantastic  nature  philosophy 
of  Timeeus,  men’s  interest  in  empirical  knowledge  turned 
the  more  exclusively  to  the  phenomena  of  the  inner  life. 
This  led  to  the  beginnings  of  an  empirical  psychology  whose 
justification  is  recognized  in  the  oft-repeated  statement  that 
the  knowledge  of  reality  divides  into  two  branches,  physica 
corporis  and  physica  anirnce.  Empirical  psychology  was,  of 
course,  developed  in  the  manner  of  the  time.  Psychology, 
among  other  things,  is  not  content  to  describe  and  classify 
mental  processes  but  seeks  to  view  them  teleologically  as 
well.  It  is  the  history  of  the  soul  which  is  to  be  expounded, 
and  the  Scholastic  writers  accordingly  appear  not  as  cau- 
tious scientists  but  as  pious  souls  yearning  to  comprehend 
the  divine  mysteries  and  thus  to  share  in  the  divine  favor. 

The  first  beginnings  of  psychological  reflection  from  an'N 
empirical  point  of  view  are  to  be  found  in  the  older  nomi- 
nalism.1 The  author  of  the  conceptualistic  treatise  De  In- 
telledibus  teaches  the  close  connection  between  sense-per- 
ception and  thought  ( sensus  and  intellectus)  .2  Between 
these  stands  the  sensuous  imagination  (imaginatio) , whose 
contents,  like  those  of  sense-perception  itself,  are  said  to  be 
indistinct  ( confusa  animcB  perceptio ).  One  calls  to  mind 
here  the  role  which  the  alleged  indistinctness  of  sense-per- 
ception played  in  the  theory  of  knowledge  subsequent  to 
Descartes  and  the  reflex  influence  it  exerted  upon  physio- 
logical psychology.  Already  in  the  tenth  century  the  \ 
three  higher  cognitive  faculties  ( intellectus , ratio,  mens)  are  de- 
scribed as  sensus  animi  by  a nominalistic  glossarist;  the  fac- 


1 Cf.  Siebeck,  op.  cit.,  I,  pp.  384  ff. 

2 See  Cousin’s  edition  of  Abelard,  II,  p.  732. 


\J 


52 


HISTORY  OF  PSYCHOLOGY 


ulties  of  the  soul  are  localized  in  the  three  ventricles  of  the 
brain  ( folliculi ),  in  which  the  principalitas  vitas,  sensus,  and 
motus  have  their  seat.1  Nevertheless,  the  traditional  lore 
from  which  the  Occident  benefited  before  the  introduction  of 
Arabian  philosophy  was  sufficiently  meagre.  The  teaching 
of  Damascenus  concerning  the  mental  faculties  and  their 
respective  functions  seems  to  have  been  held  in  peculiar 
esteem.2  This  writer  contents  himself,  in  the  sketch  referred 
to,  with  a meagre  enumeration  of  the  best-known  psychical 
states;  in  the  discussion  of  the  will,  for  example,  six  leading 
concepts  ( consilium , judicium,  sententia,  eledio,  impulsus, 
usus ) are  dismissed  with  a few  lines. 

The  influence  of  Arabian  culture  upon  psychology  was 
mediated  through  the  translations  and  adaptations  of  Con- 
stantine of  Carthage,  who  flourished  in  the  second  half  of 
the  eleventh  century.3  Constantine’s  view  of  the  nature  of 
the  soul  represents  a superficial  admixture  of  Aristotelian 
and  Platonic  conceptions.4  The  soul  is  treated  as  specifi- 
cally different  from  the  body.  It  is  the  primary  cause  of 
life,  the  secondary  being  pneuma,  which  acts  by  means  of 
special  physiological  processes.  The  different  manifesta- 
tions of  the  function  of  cognition  correspond  to  the  anatomi- 
cal divisions  of  the  brain.  The  pneuma  of  the  anterior  ven- 
tricle yields  sensation  and  perception,  that  of  the  posterior, 
movement  and  memory.  In  detail,  his  exposition  resembles 
fairly  closely  that  of  Galen.  Among  those  most  immedi- 
ately influenced  by  Constantine  is  William  of  Conches.5 
His  definition  of  the  soul  as  spiritus  corpori  conjundus  is, 
indeed,  meagre  enough.  Of  real  importance,  however,  are 
the  unmistakable  beginnings  of  genetic  psychology  made  by 


1 Barach,  Zur  Geschichte  d.  Nominalismus  von  Roszellin,  1866,  pp.  9 ff. 

2 John  Damascenus,  De  ortliod.  fid.,  II,  cap.  13  ff. 

3 Siebeck,  op.  dt.,  I,  pp.  527  ff. 

* De  commun.  medic,  cogn.  necess.  loc.  (ed.  Bas.),  IV,  1. 

6 Siebeck,  op.  dt.,  I,  pp.  531  ff. 


DESCRIPTIVE  PSYCHOLOGY 


53 


this  writer.  A number  of  faculties  mediate  between  percep- 
tion and  understanding  {ratio).  The  understanding,  which 
knows  physical  causes,  becomes  intelligence  when  knowledge 
extends  to  the  non-physical,  and  this  development  has  actu- 
ally taken  place  in  the  process  of  historical  evolution.1 

In  John  of  Salisbury  we  meet  a similar  effort  to  connect 
genetic  ideas  with  a fundamentally  Platonic  theory  of  the 
nature  of  the  soul.2  His  attempt  to  exhibit  the  development 
of  the  various  grades  of  mental  functions  from  sense-percep- 
tion is  a partial  anticipation  of  the  type  of  genetic-sensual- 
istic  psychology  destined  later  to  become  so  familiar  on 
British  soil.  The  complete  execution  of  this  task  was  ren- 
dered impossible,  of  course,  by  the  limited  knowledge  of  the 
time.  Sense-perception  is  called  a combination  of  sensa- 
tion and  judgment.3  A series  of  higher  judgments  leads  up 
to  conviction  (ratio)  which  has  its  seat  in  the  brain  between 
imagination  ( cella  phantastica)  and  memory.  As  ratio  is 
superior  to  the  senses,  it  is  in  turn  subordinated  to  intellect, 
which,  in  spite  of  the  divine  enlightenment  it  receives,  de- 
pends upon  sense-perception.  Empirical  psychology  did 
not  pass  beyond  these  beginnings  until  its  contact  with 
Arabian  science. 

Avicenna  (980-1037),  the  celebrated  teacher  of  philosophy 
and  medicine  at  Ispahan,  left  behind  him  a body  ol  empirical 
psychology  which  became  the  common  heritage  of  the  vari- 
ous branches  of  Scholasticism.4  He  separated  philosophical 
psychology  from  medical  psychology,  although  his  empirical 
investigations  do  not  carry  him  far  beyond  an  elaborate  sys- 
tem of  classification.  In  his  theory  of  sensation,  for  example, 
he  distinguishes  eight  pairs  of  contrasting  sense  qualities, 

1 See  Cousin,  CEuvr.  ined.  d’Ab.,  pp.  671  ff. 

2 Siebeck,  op.  cit.,  I,  pp.  518  ff. 

3 Primum  judicium  viget  in  sensu ; Metalogicus,  1159-60,  IV,  11, 
p.  892. 

4 Siebeck,  op.  cit.,  II,  pp.  22  ff. 


54 


HISTORY  OF  PSYCHOLOGY 


four  for  the  sense  of  touch,  and  one  for  each  of  the  remaining 
senses.  The  various  parts  of  the  soul  are  subdivided  also, 
while  each  of  the  three  kinds  of  anima  vegetativa  is  in  turn 
split  up  into  smaller  divisions.  The  relation  of  body  and 
soul  is  conceived  from  a peculiar  teleological  point  of  view. 
Each  soul,  namely,  belongs  to  that  particular  body  for  which 
it  is  best  fitted.  The  attempt  to  construct  a genetic  concep- 
tion is  suggested  by  the  doctrine  that  the  principles  of  knowl- 
edge, although  innate,  can  develop  only  in  the  wake  of  per- 
ception. To  be  sure,  this  reflection  loses  much  of  its  force 
through  the  assumption  that  the  senses  are  capable  only  of 
sensation,  true  knowledge  being  the  exclusive  product  of  the 
soul. 

With  the  incorporation  of  the  views  of  Avicenna  into  the 
theological  system  of  Alexander  of  Hales  (d.  1245)  1 we 
reach  the  point  in  mediaeval  psychology  where  the  older  Pla- 
tonic characterizations  yield  before  the  influence  of  Aristotle. 
Alexander  again  distinguished  mental  faculties  from  vital 
functions,  defining  the  soul  as  a thinking  and  active  sub- 
stance whose  continuous  activity  constitutes  life.  The  orig- 
inal active  power  of  the  soul  is  desire  (appetitus),  which  has 
as  its  aim  the  unification  of  potentiality  and  actuality. 

More  closely  related  to  the  ancient  models,  the  exposition 
of  Thomas  Aquinas  adds  to  the  Aristotelian  system  only  an 
elaborate  conceptual  apparatus.  The  relation  of  the  soul 
to  the  mental  faculties  is  the  same  as  that  of  substance  and 
accident.  The  soul  alone  is  the  subject  of  reason  and  the 
rational  will,  while  the  organism  as  a whole  serves  as  the 
basis  of  the  vegetative  and  the  sensitive  functions.  The  con- 
trast between  the  higher  and  the  lower  functions  of  the  soul 
thus  reappears  in  this  rationalistic  form. 

The  gradually  awakening  epistemological  interest  of  the 
time  finds  expression  in  the  psychological  theories  of  Roger 
1 Siebeck,  op.  cit.,  II,  pp.  180  ff. 


DESCRIPTIVE  PSYCHOLOGY 


55 


Bacon.1  The  lower  and  the  higher  faculties  of  cognition 
are  for  him  two  different  stages  of  the  same  inner  experience 
which  arises  partly  out  of  sense-impressions  and  is  partly 
of  a transcendent  origin.  Neither  are  intellect  and  will  two 
separate  powers,  but  functions,  rather,  of  one  and  the  same 
fundamental  psychical  faculty,  a doctrine  which  makes  Ba- 
con the  immediate  predecessor  of  a more  influential  writer, 
Duns  Scotus.  The  most  thoroughgoing  efforts  to  arrive  at 
a psychological  theory  of  the  process  of  knowledge,  however, 
were  made  by  Occam.2  The  external  object,  in  virtue  of  its 
own  peculiar  quality,  gives  rise  to  a sense-impression  which 
is  perceived  by  the  sensuous  soul  ( apparitio ).  Through  an 
act  of  abstraction,  which  is  a function  of  the  inner  sense 
(phantasticum) , the  conscious  perception  becomes  an  inner 
image.  Sense -perceptions  and  their  reproductions  are  now 
elaborated  by  the  intellect,  which,  through  a process  of  ab- 
straction, forms  concepts  and  judgments,  affirmative  and 
negative  judgments  being  formed  through  the  co-operation 
of  the  will.  This  psycho-epistemological  sketch  serves  to 
illustrate  how  far  these  ancient  thinkers,  although  laboring 
under  the  limitations  of  the  faculty  psychology  with  its  bar- 
ren intellectualism,  succeeded  in  analyzing  an  important 
process  like  that  of  cognition. 

Whether  we  are  to  see  in  the  psychology  of  Scholasticism 
as  a whole  the  final  phases  of  the  tradition  of  antiquity  or  the 
beginnings  of  modern  empirical  psychology  need  not  be  de- 
cided here.  In  any  case,  the  psychology  of  the  Renaissance, 
to  which  we  now  turn,  presents  a different  picture  in  both 
respects. 

1 Siebeck,  op.  cit.,  Ill,  pp.  177  ff. 

2 Siebeck,  op.  cit.,  X,  pp.  317  ff. 


56 


HISTORY  OF  PSYCHOLOGY 


(c)  The  Psychology  of  the  Renaissance 

Z One  of  the  best  evidences  of  the  stimulating  effect  upon 
/ psychology  produced  by  the  vital  participation  in  all  phases 
of  life  so  characteristic  of  the  period  of  the  Renaissance  is 
the  psychology  of  Ludovicus  Vives  (1492-1540).  His  prin- 
cipal work,  Be  Anima  et  Vita  (Bruges,  1538),  which  exerted  a 
large  influence  upon  the  psychological  theories  of  the  six- 
teenth and  seventeenth  centuries,  is  characterized  by  a defi- 
/ nitely  empirical  point  of  view.  The  task  of  psychology  is  to 
discover  the  manner  of  the  soul’s  activity.  Psychological 
description  must  be  rigorously  faithful  to  experience.  Al- 
though the  investigation  still  employs  the  tools  and  concep- 
tions of  faculty  psychology,  there  are  suggestions  of  a sort 
/ of  physiological  psychology  which  brings  the  concepts  of 
soul  and  body  into  close  relation.  Vives,  moreover,  proves 
himself  emancipated  from  the  Aristotelian  school  by  treat- 
ing the  brain  as  the  seat  of  psychical  processes. 

The  influence  of  the  new  knowledge  upon  the  various  ten- 
dencies and  directions  of  ancient  psychology  is  also  clearly 
discernible.  With  the  recrudescence  of  Platonic  psychology 
the  whole  swarm  of  ancient  psychological  conceptions  again 
became  current,  and  in  their  mutual  contradiction  the  scep- 
ticism of  the  period  found  a ready  support.  In  the  chapter 
On  the  Soul  in  his  book,  Be  Incertitudine  et  Vanitate  Scien- 
tiarum  (1527),  a work  characteristic  of  this  tendency, 
Agrippa  of  Nettesheym  makes  a collection  of  these  contradic- 
tions; but,  while  referring  to  the  fiendish  Aristotle  and  the 
divine  Plato,  he  himself  sceptically  refrains  from  expressing 
any  opinion  of  his  own  concerning  the  soul. 

More  definite  opinions  are  expressed  by  certain  philoso- 
phizing physicians  of  the  time  of  Paracelsus,  whose  psychol- 
ogy represents  a fusion  of  traditional  conceptions  with  the  new 


DESCRIPTIVE  PSYCHOLOGY 


57 


doctrine  of  Archeus.  Paracelsus  himself  fantastically  trans- 
formed many  of  the  older  teachings.  He  abandoned  the 
time-honored  doctrine  of  temperaments  taught  by  Galen, 
substituting  for  the  four  elements  the  main  principles  of 
alchemy,  sulphur,  salt,  and  mercury.  This  tendency  is  also 
represented  by  the  chemist  Van  Helmont,  who  distinguishes 
the  sensitive  soul  ( anima  sensitiva),  whose  seat  is  the  duum- 
virate, from  spirit  (mens),  an  imperishable  substance,  whose 
attributes  are  intelledus,  voluntas,  and  amor } The  manner 
in  which  this  part  of  the  soul,  which  is  subject  to  neither 
fatigue  nor  disease,  can  act  upon  the  others  is  left  unde- 
termined.1 2 

Connected  only  slightly  with  this  questionable  theoretical  1 
psychology,  a secular  Renaissance  psychology  is  developed 
which  we  can  recognize  as  a forerunner  of  the  empirical 
ps^hology  of  the  eighteenth  century.  The  doctrines  of  ( 
temperaments,  astrology,  and  physiognomy  here  stand  in 
*^the  service  of  a realistic  characterology.  Juan  Huarte’s 
Examen  de  ingenios  (1575)  thus  teaches  an  individual  psy- 
chology which  seeks  to  bring  the  mental  traits  of  the  indi- 
vidual into  relation  with  bodily  constitution.  With  the 
French  psychologists  of  this  period,  beginning  with  Michel 
de  Montaigne  (1580),  this  individual  psychology  tends  more 
and  more  to  become  practical  anthropology.3 

More  important  than  these  fantastic  or  superstitious  ideas 
and  this  secular  psychology  is  the  controversy  between  the 
traditional  faculty  psychology  and  the  new  conception  of 
soul  substance  which  was  already  preparing  in  the  Marburg 
school.  Casmann4  does  not,  indeed,  explain  the  relation  be- 

1 Cf.  Strunz,  “Die  Psychologie  des  Joh.  Bapt.  van  Helmont  in  ihren 
Grundlagen,”  Zeitschrift  f.  Phil.  u.  phil.  Kritik,  CXXV,  1905,  p.  2. 

2 Van  Helmont,  Imago  Mentis,  § 7,  Opera,  1648. 

3 Cf.  with  this  the  pregnant  discussion  of  M.  Dessoir,  Gesch.  d.  n.  d. 
Psychologie,  I,  2d  ed.,  1897,  pp.  47  ff. 

1 Psychologia  anthropologica,  1594. 


58 


HISTORY  OF  PSYCHOLOGY 


/ / tween  a unitary  soul  and  a plurality  of  faculties;  nevertheless, 
I he  raises  the  objection  that  each  faculty  requires  a second 
I faculty  for  the  explanation  of  its  peculiar  functions.  Neither 
did  the  psychology  of  Descartes  tolerate  a multiplicity  of 
i separate  faculties,  for  the  soul  has  only  a single  faculty, 
/ that  of  thought;  and  the  distinction  of  the  various  thought 
I processes,  which  all  rest  upon  the  fundamental  distinction 
between  active  and  passive  thought,  does  not  in  any  way 
jeopardize  the  underlying  unity.  The  popular  distinction 
between  a higher  and  a lower  mental  faculty  Descartes, 
clinging  closely  to  the  metaphysical  presuppositions  of  his 
' psychology,  explains  by  a supposed  conflict  between  them 
i in  the  pineal  gland  in  which  a movement  set  up  by  the  ani- 
mal spirits  in  the  body  meets  another  movement  set  up  by 
the  soul  through  the  activity  of  the  will.  For  the  rest,  the 
distinction  between  power  and  faculty  does  not  as  yet  Aist 
in  the  Cartesian  psychology,  while  later  the  concept?  of 
psychical  powers  and  psychical  faculties  are  used  inter- 
changeably, a convincing  illustration  of  the  fact  that  in  the 
history  of  psychology  distinctions  of  terminology  and  of 
fact  are  difficult  to  keep  separated.1 

r ■ (d)  The  Newer  Faculty  Psychology 

j It  was  John  Locke  who,  writing  from  the  standpoint  of 
empirical  psychology,  was  the  first  to  urge  emphatically 
against  faculty  psychology  those  objections  which  have 
become  commonplaces  in  modern  psychology.  In  the  dis- 
cussion of  the  freedom  of  the  will  he  pointed  out  the  futility 
of  the  attempt  to  explain  freedom  by  reference  to  a faculty 
\of  volition;  as  well  call  in  a vocal  faculty  to  explain  singing, 
or  a faculty  of  dancing  to  explain  dancing.  Psychology 

'See  the  following  from  the  Cartesian  Clauberg:  “Vis  facultas  po- 
tentia  quse  nihil  aliud  quam  non  repugnantia  ad  agendum.” 


DESCRIPTIVE  PSYCHOLOGY 


59 


gained  little,  however,  through  Locke’s  substitution  of  powers 
for  faculties.  This  is  evidenced  in  Locke  himself  by  his  curi- 
ous oversight  of  the  mutual  interaction  of  mental  processes. 
The  separate  powers  no  more  influence  one  another  than 
the  power  to  sing,  for  example,  influences  the  power  to 
dance.  In  the  enumeration  of  mental  powers,  moreover, 
Locke  was  hardly  less  generous  than  faculty  psychology. 
Leibniz  transformed  the  concept  of  faculty  into  that  of  ac- 
tual tendency,  and  he  was  able  to  dispense  with  the  swarm 
of  faculties  the  more  easily  inasmuch  as  his  doctrine  of  the 
persistence  of  petites  perceptions  permitted  him  to  refer  what 
were  apparently  novel  phenomena  to  their  temporal  ante- 
cedents. 

In  Christian  Wolff  (1679-1754),  who  first  employed  the 
term  mental  faculty,  the  Leibnizian  tendency  was  directly 
con^nued.1  In  his  rational  psychology  he  designates  the 
power  of  representation  (vis  reprcesentativa ) as  the  funda- 
mental power  of  the  soul.  This  is  the  sufficient  reason  for 
every  mental  phenomenon,  in  so  far  as  it  transforms  the 
possibilities  of  psychical  processes,  i.  e.,  the  faculties,  into 
actualities.  On  the  ground  of  the  conceptual  discriminations 
attempted  by  Leibniz,  therefore,  power  and  faculty  are  kept 
distinct,  thus  resulting  in  a distinction  which  goes  back 
directly  to  the  Aristotelian  Surn/zt?  and  ivepyeca.  But 
Wolff'  does  not  remain  long  upon  these  heights  of  abstrac- 
tion. The  faculties,  which  in  the  beginning  are  mere  possi- 
bilities of  mental  processes,  now  become  attributes  of  the 
soul ; at  first  mere  nudce  agendi  possibilitates,  they  now  turn 
into  the  more  substantial  forms  of  natural  dispositions,  so 
much  so  that  their  relation  to  the  mind  can  be  compared 
with  the  relation  of  bodily  organs  to  the  body.  The  classifi- 
cation of  these  faculties  is  based  upon  the  overlapping  oppo- 

1 Wolff,  Psychologia  rationalis,  1734;  Psychologia  empirica,  1732.  The 
difference  between  the  two  treatises  is  less  than  the  titles  would  suggest. 


60 


HISTORY  OF  PSYCHOLOGY 


sites  of  cognition— desire,  and  of  sense — reason.  In  the  first 
pair  of  faculties  the  Leibnizian  distinction  between  cognition 
and  appetition  as  attributes  of  the  monad,  a distinction  to 
which  Wolff  always  adhered,  is  clearly  discernible.  While 
cognition  and  desire  (the  latter  term  also  includes  feeling) 
are  here  juxtaposed  without  any  difference  of  valuation,  the 
second  principal  division  yields  a lower  and  a higher  faculty 
of  cognition,  as  also  a lower  and  a higher  faculty  of  desire. 
In  the  subdivisions  of  these  four  principal  faculties,  mean- 
while, there  is  not  the  slightest  attempt  at  system.  Even 
the  most  complex  mental  faculties  are  “explained”  by  in- 
voking the  magic  words  mental  faculty.  In  his  attempt  to 
explain  the  interaction  of  the  various  faculties  each  faculty 
functioned  as  a sort  of  intelligence  or,  at  least,  had  enough 
in  common  with  the  faculty  of  intelligence  to  render  intelli- 
gent co-operation  among  the  faculties  possible.  The  parl- 
ous grades  of  intelligence,  furthermore,  could  readily  be  rep- 
resented on  the  analogy  of  the  Leibnizian  distinction  between 
clear  and  obscure  perceptions. 

'/There  is  not  a writer  in  the  history  of  faculty  psychology 
after  Aristotle  who  gives  so  much  attention  to  mental  facul- 
ties as  Wolff.  With  Descartes  the  contrast  between  the 
active  and  passive  mental  processes  had  received  the  prime 
emphasis;  Locke  had  designated  sensation  and  reflection  as 
distinct  sources  of  knowledge;  in  Leibniz,  finally,  the  princi- 
ple of  psychological  explanation  of  primary  importance  was 
the  power  of  representation.  It  must,  of  course,  be  remem- 
bered that  Wolff  passed  into  only  a part  of  the  Aristotelian 
j heritage,  which  had  been  the  common  possession  of  scientific 
thought  for  so  many  centuries.  He  was  incapable  of  the 
painstaking  and  ingenious  methods  of  investigation  charac- 
teristic of  Aristotle.  His  empirical  psychology,  in  fact,  is 
little  more  than  a questionable  determination  of  the  number 
and  the  character  of  mental  faculties. 


DESCRIPTIVE  PSYCHOLOGY 


61 


A 


In  the  Wolffian  school  the  doctrines  of  faculty  psychology 
were  extended  to  the  cognate  sciences,  like  ethics,  in  the  ra- 
tional utilitarianism  of  which  it  readily  struck  root,  and 
aesthetics,  which  contented  itself  for  a long  period  with  call- 
ing the  creative  imagination  a lower  order  of  the  faculty  of 
cognition.  In  spite  of  the  arbitrary  manner  in  which  they 
were  deduced,  the  Wolffian  distinctions  long  maintained  their 
influence.  When  we  come  to  examine  in  detail  the  faculty 
psychology  of  the  eighteenth  century  emanating  from  Wolff 
we  find  it  to  be  an  achievement  of  doubtful  value.  It  must 
not  be  forgotten,  however,  that  the  real  aim  was  to  construct 
an  empirical  psychology  which  should  discover  introspec- 
tively  the  contents  of  consciousness  and  then  discover  the 
elementary  powers  of  which  they  are  the  manifestations. 
The  methods  of  description  and  classification  employed  here 
were,  as  in  many  other  branches  of  psychology,  modelled 
after  the  methods  of  the  natural  sciences.  It  will  be  remem-/ 


bered  that  the  eighteenth  century  was  the  century  of  those : 
descriptive  sciences  in  which  Linne  and  Buffon  were  mas- 
ters. To  be  sure,  attempts  at  explanation  in  the  field  of 
psychology  could  not  but  have  meagre  results.  The  follow- 
ing is  a typical  example:  If  the  power  of  imagination  com- 
bines with  the  understanding,  the  creative  faculty  results; 
if  it  combines  with  reason,  we  get  the  power  of  anticipation, 
etc.  The  attempt  to  explain,  to  reduce  the  complex  to  the 
simple,  is  sufficiently  commendable;  but  the  actual  explana- 
tion is  undertaken  with  methods  wholly  insufficient  for  the 
purpose. 

Even  the  opposition  to  the  Wolffian  psychology  did  not 
succeed  in  freeing  itself  from  the  domination  of  the  con- 
ceptions of  the  school  psychology.  Crusius  attacked  the 
doctrine  of  mental  faculties  in  his  work,  Entwurf  der  notwen- 
digen  Vernunftwahrheiten  (1745),  asserting  that  they  were 
merely  so  many  arbitrarily  abstracted  powers  which  made  a 


62 


HISTORY  OF  PSYCHOLOGY 


purely  causal  explanation  impossible.  To  meet  the  latter  de- 
mand, he  assumed  actual  powers  in  the  soul  substance  which 
itself  remained  simple.  There  are  mental  powers  of  first 
order,  like  consciousness  and  sensation;  of  the  second  order, 
like  imagination  and  the  capacity  for  incomplete  ideas.  In 
spite  of  the  strong  emphasis  upon  causal  explanation,  these 
determinations  are  still  distinctly  reminiscent  of  the  point  of 
view  of  the  faculty  psychology.  The  psychological  disciples 
of  Bonnet,  men  like  Irwing,  Lossius,  and  Hissmann,  schooled 
as  they  were  in  the  methods  of  physiology,  passed  a more 
effective  criticism  upon  the  old  doctrine  of  mental  faculties. 
They  were  themselves,  however,  not  free  from  the  inclina- 
tion to  explain  the  various  conscious  processes  by  reference 
to  some  single  fundamental  power.  As  a rule,  sensation, 
which  was  thought  of  as  a reaction  of  the  soul  to  the  exci- 
tation of  nerve  fibres,  figured  as  such  a fundamental  power. 
Tetens  (1736-1805)  criticised  this  view  on  the  ground  that 
perception  and  judgment  were  thus  treated  as  belonging  on 
the  same  plane  as  sensation,  while  he  himself  held  that  sen- 
sation, perception,  and  thought  were  distinguished  only  in 
the  degree  of  self-activity  which  the  soul  displayed. 

Tetens,  meanwhile,  made  an  important  contribution  to 
the  school  psychology.1  He  effected  a breach  in  the  Wolffian 
scheme  by  the  addition  of  a new  faculty,  that  of  feeling,  to 
those  sanctioned  by  the  Wolffian  tradition.  * Tetens  proposed 
a new  pair  of  fundamental  mental  activities.  In  his  attempt 
to  “reduce  the  various  capacities  to  the  simplest  faculties) 
and  to  penetrate  to  the  primary  origins  of  these  faculties  in 
some  fundamental  power,”  he  comes  upon  the  opposites  of 
receptivity  and  activity.  The  first  is  feeling,  the  second 
embraces  the  various  activities  of  will,  the  inner  activities 
of  idea  and  thought  as  well  as  the  outer.  Thus  originated 
the  tripartite  division  of  feeling,  cognition,  and  will,  which 
was  destined  to  dominate  psychology  for  a long  time  to  come. 

1 Versuche  uber  die  menschliche  Natur,  1776-7,  pp.  4,  7. 


DESCRIPTIVE  PSYCHOLOGY 


63 


The  rationalistic  origin  of  the  scheme  is  evident  from  the 
description  of  feeling,  ideation,  and  thought  as  phases  or 
subdivisions  of  the  general  faculty  of  cognition. 

Both  of  the  above  classifications  meet  us  again  in  Kant. 
Sense  and  understanding,  the  receptive  and  the  spontaneous 
sides  of  mental  life,  appear  as  lower  and  higher  faculties  of 
cognition.  Cognition,  feeling,  and  desire,  on  the  other  side, 
appear  as  three  fundamental  faculties,  separate  and  irre- 
ducible. The  Leibnizian  distinction  between  faculty  and 
power,  on  the  other  hand,  disappears.1  Furthermore,  Kant 
proposes,  as  correlatives  of  concept,  judgment,  and  conclu- 
sion in  logic,  the  trichotomy  of  the  higher  faculty  of  cog- 
nition into  understanding,  reason,  and  judgment.  For  the 
relation  of  these  three  phases  of  the  higher  faculty  of  cog- 
nition to  the  principal  faculties  of  the  mind  mentioned  above, 
the  relation  of  reason  to  the  faculty  of  desire  appears  to  have 
been  normative.  Reason,  as  the  faculty  of  ideas,  could  have 
a constitutive  significance  only  in  the  sphere  of  practical 
conduct.  Since  the  understanding  coincided  with  the  fac- 
ulty of  cognition,  feeling  naturally  came  under  the  faculty 
of  judgment.  In  so  far  as  this  schematization  took  into 
account  only  the  higher  manifestations  of  the  faculties 
concerned,  it  exercised  an  unfavorable  influence  upon  the 
psychological  treatment  of  the  three  fundamental  faculties. 
Furthermore,  the  sharp  separation  of  the  fundamental  fac- 
ulties obscured  the  fact  of  their  essential  unity  and  the 
fruitless  interaction  of  faculties  everywhere  took  the  place 
of  the  actual  phenomena  of  the  mental  life.  Fortunately, 
Kant  did  not  adhere  to  the  schematism  of  the  three  Critiques 
in  his  principal  psychological  work,  Anthropologie,  but  pre- 
sented instead  a body  of  practical  psychology  which  he  had 
inherited  from  the  Enlightenment  and  which  is  still  worthy 
of  study  to-day. 

The  Kantian  faculty  psychology  was  continued  by  his 

1 Cf.,  e.  g.,  Krug,  Philosophisches Lexikon  (1827-34),  article  “Kraft.” 


64 


HISTORY  OF  PSYCHOLOGY 


school.  K.  L.  Reinhold  sought  to  explain  the  several  varie- 
ties of  the  faculty  of  cognition  by  reference  to  the  faculty  of 
ideation  or  representation.  Representation  without  a fac- 
ulty of  representation  is  to  him  unthinkable.  He  even  be- 
lieved himself  to  be  acting  in  particular  sympathy  with  the 
spirit  of  Kant  when  he  substituted  the  investigation  of  men- 
tal faculties  for  the  investigation  of  the  mind  itself.  For 
the  same  reason  he  keeps  in  strict  separation  the  representing 
subject  from  the  faculty  of  representation.  The  former  de- 
termines the  attributes  of  the  faculty  of  representation  merely 
in  a logical,  not  in  a real  sense.  J.  F.  Fries  (1773-1843)  in- 
sisted upon  a sharp  separation  of  philosophical  anthropology 
and  empirical  psychology.  The  latter  is  an  experimental 
physics  of  the  inner  life,  whereas  the  former  is  a theory  of 
this  life,  bearing  about  the  same  relation  to  empirical  psy- 
chology as  the  philosophy  of  nature  holds  to  physics.  Fries 
grants  to  the  usual  conceptual  determinations  of  mental 
faculties  only  a descriptive  significance  and  demands  their 
proof  by  philosophical  anthropology.  These  faculties  must, 
furthermore,  be  subordinated  to  general  laws.1  All  causal 
relations  of  inner  experience  must  be  ascribed  to  a faculty 
as  cause,  not  to  an  activity  as  its  manifestation.  So  long  as 
the  activity  of  a faculty  consists  only  in  modifying  other 
faculties  in  respect  to  their  manifestations,  as  will,  e.  g., 
acts  upon  attention,  they  are  intermediate  faculties.  But 
they  themselves  have  as  their  ground  the  primary  faculties 
which  manifest  themselves  on  their  own  account  and  act 
according  to  a law  of  their  own  activity,  as,  e.  g.,  thought 
and  cognition.  Nevertheless,  mental  faculties  are  not  sus- 
ceptible of  classification  as  are,  for  example,  plants  and  ani- 
mals, for  all  the  fundamental  dispositions  are  active  in  ev- 
ery vital  function,  only  in  different  degrees.  The  difficulty 
growing  out  of  this  conception  Fries  attempts  to  meet  with 
1 Neue  Kritik  der  Vernunft,  1807,  §§  5-8. 


DESCRIPTIVE  PSYCHOLOGY 


65 


his  doctrine  of  the  stages  of  mental  development.  There 
are  distinguishable  in  each  of  the  three  fundamental  faculties 
three  stages,  sense,  habit,  and  understanding.  If  we  add  to 
these  the  two  fundamental  opposites  of  spontaneity  and  re- 
ceptivity, which  repeat  themselves  at  every  stage  of  develop- 
ment, we  see  how  prolix  the  faculty  psychology  again  be- 
comes in  the  hands  of  a man  who  had  come  to  understand 
the  inadequacy  of  it  in  its  traditional  form. 

The  theory  of  faculties  is  so  natural  as  an  explanatory 
hypothesis  that  we  can  trace  its  influence  even  in  tenden- 
cies of  modern  psychology  not  directly  dependent  upon  the 
traditional  sources.  The  so-called  psychological  school  in 
France,  for  example,  bears  the  impress  of  the  faculty  psy- 
chology during  the  first  third  of  the  nineteenth  century.  It 
is  true  that  Jouffroy  demanded  the  separation  of  psychology 
both  from  philosophy  and  from  physiology.  His  own  psy- 
chological observation,  however,  offers  little  that  is  new,  and 
his  assumption  of  six  original  mental  faculties  differs  from 
the  customary  classification  only  in  the  systematic  character 
of  his  own  scheme.  The  case  is  similar  with  the  celebrated 
physicist  and  student  of  the  classification  of  the  sciences, 
Ampere,  although  he  does,  of  course,  make  an  attempt  to 
explain  the  connection  of  psychical  processes  by  his  theory 
of  “concretions,”  the  theory  that  sensations  spontaneously 
combine  with  remembered  previous  impressions  to  form 
groups  or  “concretions.” 

The  decisive  step  in  the  history  of  faculty  psychology  was 
destined  to  be  taken  in  Germany.  Faculty  psychology  had 
already  come  in  for  its  share  of  criticism  in  the  reaction  to 
the  Kantian  system,  as  in  the  case  of  Schulze-/Enesidemus, 
who  characterized  the  faculty  theory  as  a mythological  treat- 
ment of  psychology.  The  real  turning-point,  however,  in 
the  history  of  the  faculty  theory  was  signalized  by  Herbart’s 
memorable  criticism.  There  are  two  principal  objections 


66 


HISTORY  OF  PSYCHOLOGY 


/hich  remove  the  foundations  from  the  faculty  theory.  The 
first  is  that  the  mental  faculties  are  mere  class  concepts  which 
are  derived  from  experience  by  a process  of  provisional  ab- 
straction and  cannot  rightly  be  raised  to  the  dignity  of 
fundamental  powers.  In  the  second  place,  mental  faculties 
are  nothing  more  than  possibilities,  which  are  not  found 
among  the  facts  of  inner  experience.  For  it  is  only  the  par- 
ticular idea,  not  a faculty  of  ideation,  the  particular  feeling, 
not  a faculty  of  feeling,  which  forms  the  content  of  our  actual 
experience.  But  from  the  mere  possibility  the  real  happen- 
ing can  never  be  derived.  The  first  of  these  objections 
applies  primarily  to  the  doctrine  of  the  plurality  of  separate 
faculties.  There  is  a certain  relationship,  indeed,  between 
the  psychological  class  concept  and  other  classifications, 
such  as  have  been  formed,  for  example,  in  the  history  of 
the  life  sciences.  How  rich,  for  example,  was  the  physiology 
of  Romanticism  in  organ-building  powers ! In  this  respect 
psychology  only  shares  the  fate  of  all  the  other  sciences. 
But,  whereas  the  expanding  knowledge  of  facts  leads  to  a re- 
duction of  such  superfluous  notions  of  power  in  the  natural 
sciences,  faculty  psychology  demands  their  indefinite  mul- 
tiplication. The  faculty  of  memory,  for  example,  divides 
into  a whole  series  of  special  memories,  such  as  verbal  mem- 
ory, memories  for  numbers,  persons,  etc.,  which  eventually 
turn  out  to  be  as  different  from  one  another  as  the  faculty 
of  memory  is  different  from  that  of  imagination.  The  sec- 
ond objection  attacks  the  notion  of  faculty  directly.  Her- 
bart  proposes  to  substitute  for  it  the  notion  of  power,  which 
differs  from  faculty  in  the  respect  that  it  arises  as  a neces- 
sary result  of  the  appropriate  conditions.  We  thus  arrive 
at  the  most  important  point  of  view  in  which  explanatory 
psychology  goes  beyond  a merely  descriptive  psychology. 
In  the  faculty  psychology  mental  faculties  have  free  play, 
but  when  the  notion  of  faculties  has  once  fallen  to  the 


DESCRIPTIVE  PSYCHOLOGY 


67 


ground  the  question  as  to  the  conditions  under  which  given 
kinds  of  mental  processes  regularly  run  their  course  can  arise. 

One  last  phase  of  the  faculty  psychology  remains  to  be 
mentioned.  F.  E.  Beneke  (1798-1854)  made  the  singular  at- 
tempt to  bring  about  the  dissolution  of  faculty  psychology  by 
giving  the  tendency  to  unlimited  specialization  of  faculties  \ 
unrestricted  play.  The  idea  that  every  new  mental  process 
meant  the  development  of  another  specific  faculty  modi- 
fied the  whole  conception  of  mental  faculties  in  a peculiar 
way.  Faculties  are  for  Beneke  no  longer  mere  empty  pos- 
sibilities. They  rather  stand  for  an  undetermined  psy- 
chical occurrence  within  the  sphere  of  the  unconscious,  which 
occasionally  enters  consciousness.  They  are  also  described 
as  tendencies  which  seek  realization  through  sensation.  Thus 
Beneke,  although  in  his  method  more  nearly  allied  to  the 
psychology  of  the  inner  sense,  approaches  Herbart,  whose 
ideas  are  often  merely  couched  in  a different  terminology. 

In  this  singular  manner  two  tendencies  so  opposite  as  the 
faculty  psychology  and  psychical  mechanics  meet  each  other. 
Beneke’s  primitive  faculties  are,  taken  fundamentally,  Her- 
bart’s  simple  representations.  Corresponding  to  the  fusions 
and  complications  in  Herbart,  we  have,  in  Beneke,  the  flow- 
ing together  and  the  flowing  through  each  other,  in  opposite 
directions,  of  the  mobile  elements  of  the  soul.  The  power 
of  the  primitive  faculty  to  cause  itself  to  be  filled  and  filled 
to  overflowing,  about  like  an  empty  vessel,  is,  of  course,  an 
idea  peculiar  to  Beneke. 

There  is  little  that  is  pleasing  in  the  influence  exerted 
upon  the  faculty  psychology  by  the  philosophical  systems 
of  Schelling  and  Hegel.  If  one  takes  up,  for  example,  the 
Vorlesungen  iiber  Psyckologie  of  C.  G.  Carus  (1831),  one,  in- 
deed, finds  the  author  renouncing  the  “polytheism”  of  mental 
faculties  and  extolling  the  genetic  method,  but  the  latter 
is  little  more  than  an  enumeration  of  the  various  psycho- 


68 


HISTORY  OF  PSYCHOLOGY 


logical  phenomena  which  run  their  course  in  the  history  of 
the  individual’s  life.  The  apparent  derivations  are  in  re- 
ality nothing  more  than  naive  descriptions,  and  the  analo- 
gies which  are  drawn  between  the  mind  and  processes  in 
nature,  such  as  plant  growth,  are  still  more  superficial.  G. 
H.  von  Schubert  also,  in  his  Geschichte  der  Seele,  contents 
himself  with  an  exposition,  aided  by  analogies  with  the  animal 
organism,  of  the  fundamental  tendencies  of  mental  activity, 
unconcerned  to  make  a single  psychological  analysis. 

It  was  a characteristic  assertion  of  Hegel’s  that  the  psy- 
chological works  of  Aristotle  continued  to  be  the  most  im- 
portant, if  not  the  only,  work  of  speculative  interest  on  the 
subject.1  The  only  contribution  of  his  own  was  to  render 
fluid  the  Aristotelian  faculties  by  the  melting  process  of  his 
own  dialectic.  The  Hegelian  psychology,  as  this  was  de- 
veloped in  the  spirit  of  Hegel  by  Rosenkranz,  Michelet,  and 
Erdmann,  was  sharply  criticised  by  F.  Exner,2  who  charged 
that  this  mechanical  system  meant  a relapse  of  psychology 
even  beyond  Wolff  himself.  It  is  in  this  criticism  that  we 
see  scientific  thought  making  a determined  stand  against 
the  speculative  thought  of  the  past. 

With  this  the  faculty  psychology  may  be  said  to  have 
come  to  a definite  end.  Its  long  reign  illustrates  how  tar- 
dily exact  thought  turned  its  attention  to  the  actual  psychi- 
cal facts  embedded  in  prescientific  conceptions.  Faculty 
psychology  ignored  the  fact,  particularly,  that  through  the 
fusion  of  simple  processes  combinations  which  are  qualita- 
tively novel  can  arise.  It  acknowledged  only  the  innate  fac- 
ulties and  the  empirical  contents  of  the  mind  with  which  they 
work.  Thus  almost  the  whole  psychology  of  Greek  an- 
tiquity started  with  the  assumption  that  mental  contents 

1 Enzyklopadie,  1817,  § 378. 

2 Die  Psychologie  der  Hegelschen  Schule,  beurteilt  von  Dr.  F.  Exner , 
1842. 


DESCRIPTIVE  PSYCHOLOGY 


69 


either  originate  in  sense-perception  or  that  they  are  an  in- 
nate possession  of  the  soul.  The  most  significant  testimony 
of  this  is  Plato’s  theory  of  ideas,  that  mystical  recollection 
by  the  soul  of  contents  which  could,  according  to  their  def- 
inition, not  have  originated  in  experience.  Although  this 
alternative  was  probably  primarily  of  an  epistemological 
origin,  it  dominated  psychology  for  a long  period.  To  over- 
come it  required  a methodological  apparatus  which  was  im- 
possible until  the  advent  of  analytic  psychology.  Faculty 
psychology,  meanwhile,  has  the  lasting  merit  of  having 
anticipated,  in  a general  way,  the  aims  of  descriptive  psy- 
chology and,  furthermore,  of  having  occupied  itself  with  a 
problem  with  which  every  system  of  psychology  must  deal, 
that  of  the  classification  of  mental  processes.  It  was  faculty 
psychology  that  drew  the  principal  distinctions  out  of  which 
the  classifications  of  analytical  psychology  were  to  grow. 


2.  The  Psychology  of  the  Inner  Sense 

Opposed  to  faculty  psychology  are  all  systems  of  psychol- 
ogy which  employ  in  common  some  form  of  analysis.  For 
it  is  through  the  analysis  of  phenomena  that  prescientific 
concepts  become  scientific  concepts.  Psychological  analysis, 
however,  has  a uniqueness  which  sets  it  off  from  other  forms. 
The  data  of  psychology,  namely,  have  the  peculiarity  which 
we  designate  by  calling  them  experiences,  without  being 
able  to  give  a more  definite  description  of  them.  With  the 
attempt  to  lay  hold  upon  these  data  the  fundamental  dis- 
tinction between  physical  and  psychical  phenomena  became/ 
apparent.  Introspection  was  found  to  be  a wholly  different 
process  from  the  observation  of  external  phenomena,  so  that 
the  attempt  to  analyze  mental  experiences  led  to  a sharp 
separation  between  outer  and  inner  experience.  The  first 
demand  of  psychological  description  was  thus  satisfied.  But 


70 


HISTORY  OF  PSYCHOLOGY 


the  particular  form  which  the  efforts  of  descriptive  psy- 
chology took,  and  in  which  it  superseded  the  older  faculty 
psychology,  depended  upon  a still  more  general  aspect  of 
thought  of  a more  scientific  sort.  For  to  the  stage  of  the 
classification  of  phenomena  there  corresponds  some  consider- 
ation as  to  methods  of  observation.  Thus,  for  example,  the 
philosophy  of  nature  of  antiquity,  which,  in  contrast  with 
the  mythological  interpretation  of  nature,  already  under- 
took a derivation  of  complex  phenomena  from  more  simple 
ones,  early  occupied  itself  with  theories,  primitive  enough,  to 
be  sure,  of  sense-perception.  In  a similar  manner,  analysis 
within  the  sphere  of  the  psychical  is  preceded  by  reflections 
upon  the  peculiar  nature  of  inner  perception.  In  analogy 
to  the  outer  senses  the  term  “inner  sense”  became  domes- 
ticated as  a term  for  this  species  of  perception.  Now,  if  the 
inner  sense  is  to  be  directed  toward  specific  objects,  as  the 
analogy  to  the  outer  sense  suggested,  it  is  cognitive  proc- 
esses which  lend  themselves  most  readily  to  introspective 
observation.  A psychology  whose  analyses  depend  upon 
the  peculiarites  of  such  an  inner  sense  naturally  developed 
from  the  very  outset  a tendency  toward  intellectualism. 
When  such  an  intellectuaiistic  psychology  combined  with 
faculty  psychology,  logical  reflections  would  take  the  place 
of  psychological  processes  and  psychology  relapse  into  a 
prescientific  stage,  or  else  become  dominated  by  a meta- 
physical conception  of  the  soul,  as  it  was,  for  instance,  in  the 
case  of  the  rational  psychology  of  the  eighteenth  century. 

Inhere  is  a second  reason  why  cognitive  processes,  par- 
ticularly perception  or  ideation,  should  become  the  special 
Subject-matter  of  the  psychology  of  the  inner  sense.  It  is 
in  connection  with  these  that  the  fact  is  most  distinctly  ob- 
servable that,  while  ideation  is  always  directed  toward  an 
object,  the  process  of  ideation  can  itself  become  the  object 
of  introspective  observation.  In  the  case  of  a feeling,  this 


DESCRIPTIVE  PSYCHOLOGY 


71 


change  in  the  method  of  observation  would  be  less  easily 
observable. 

The  exclusive  employment  of  the  inner  sense  as  a source 
of  experience  led  eventually  to  a purely  introspective  psy- 
chology, a form  which  has  in  most  recent  times  developed 
in  close  connection  with  the  problems  of  explanatory  psy- 
chology. 

A common  distinction  made  by  the  psychology  of  the  inner 
sense  is  that  between  outer  and  inner  experience,  with  the 
demand  that  the  methods  of  investigation  in  the  two  spheres 
should  be  correspondingly  different.  Modern  psychology 
tends,  however,  to  emphasize  the  unity  of  experience,  the 
difference  between  mediate  and  immediate  depending  mainly 
upon  the  point  of  view  adopted.1  The  history  of  psychology 
did  not,  however,  start  with  these  contrasts.  The  point  of 
departure  consisted  rather  in  a phase  of  the  problem  of  inner 
perception,  the  problem,  namely,  how  it  is  possible  to  have  a 
consciousness  of  one’s  own  perceptual  activities.  It  is  not 
the  difference  among  the  phenomena,  like  feelings,  emotions, 
decisions,  etc.,  on  the  one  side,  and  colors,  tones,  etc.,  on  the 
other,  but  the  fact  that  in  the  perception  of  colors,  tones,  etc., 
we  have  also  a consciousness  of  these  perceptions  that  led 
to  the  assumption  of  a special  inner  sense.  The  inner  per- 
ception, in  the  pregnant  sense  of  the  term,  whose  object  is 
itself  an  ordinary  perceptual  process,  appears  to  us  as  a 
special  form  of  inner  experience,  as  a turning  inward  (to 
remain  within  the  same  circle  of  ideas)  of  the  inner  sense 
itself.  But,  as  happens  so  often  in  the  history  of  psychol- 
ogy, it  was  the  most  striking  phenomenon,  which  need  not 
by  any  means  be  the  simplest,  which  became  a starting- 
point  for  psychological  investigation. 

A second  point  of  view  originated  in  the  older  doctrine  of 
inner  sense  from  the  mistaken  distinction  between  sense- 
1 Cf.  Chapter  V,  3 (6). 


72 


HISTORY  OF  PSYCHOLOGY 


perception  and  its  reproductions,  reproductions  which  were 
called  memory  if  they  recurred  in  their  original  connections, 
and  imagination  if  they  were  fantastically  combined.  It 
was  the  outer  sense  which  was  active  in  sense-perception, 
the  inner,  in  memory  and  imagination.  This  external  point 
of  view  became  prominent  particularly  in  connection  with 
faculty  psychology. 

A second  and  higher  stage  of  psychological  reflection  than 
that  of  the  older  psychology  of  inner  sense  arose  when  the 
totality  of  mental  phenomena  was  conceived  as  a closed  sys- 
tem of  experience  accessible  only  to  the  inner  sense,  and 
when  the  latter  was  regarded  as  an  independent  source  of 
experience.  The  merit  of  having  taken  this  step  belongs  to 
John  Locke.  The  connection  of  psychology  with  epistemo- 
logical questions  finally  led,  in  the  second  half  of  the  cen- 
tury, to  a branch  of  psychology  which  in  a peculiar  manner 
formed  the  basis  of  a descriptive  or  phenomenological  psy- 
chology of  the  inner  sense. 

The  expression  “inner  sense”  is  one  of  the  oldest  of  Ger- 
man philosophical  terms.  As  old  a writer  as  Notker  (d. 
1022),  who,  following  the  version  of  Boethius,  was  the  first 
to  translate  the  writings  of  Aristotle  into  German,  translated 
sensus  by  “uzero  sin”  and  imaginatio,  ratio,  and  intelli- 
gentia  by  “innero  sin.”  The  term  inner  experience  {inner e 
Erfahrung)  is  of  much  later  origin,  occurring  as  Erfahrenheit 
in  the  works  of  the  mystic  Weigel  in  the  sixteenth  century. 


(a)  The  Older  Doctrine  of  the  Inner  Sense 

Scattered  observations  on  the  peculiar  nature  of  inner  per- 
ception are  found  early  in  the  history  of  psychological  reflec- 
tion. Plato  referred  to  a cognition  of  cognition,  a knowledge 
of  knowledge.  He  also  held  that  for  true  pleasure  the 
So£a  aXrjOgs  of  it  was  necessary.  But  he  did  not  continue 


DESCRIPTIVE  PSYCHOLOGY 


73 


this  addition  of  one  psychical  act  to  another,  because  it  led, 
as  he  thought,  to  an  infinite  regress.  It  was  Aristotle  who 
recognized  the  true  nature  of  the  problem  of  inner  percep- 
tion and  who  had  the  good  fortune,  in  dealing  with  the  prob- 
lem, to  make  his  beginning  at  a much  more  tangible  point. 
After  discussing  the  activity  of  outer  perception  he  raises 
the  question  by  what  activity  we  become  aware  of  the  act 
of  perception  itself  as  distinguished  from  the  objects  per- 
ceived. There  can  be  no  special  sense  for  the  perception  of 
the  act  of  perception,  according  to  Aristotle,  as  that  would 
necessitate  another  sense  for  the  perception  of  the  first. 
Accordingly,  all  the  senses  must  have  in  common  the 
power  to  perceive  themselves,  a power  which  Aristotle 
calls  the  npcorov  aiaOijpiov.  Since  this  power  also  perceives 
the  common  attributes  of  the  different  sensory  contents, 
it  is  also  called  the  common  sense  ( Gemeinsinn , kolvt) 
aiad Tjcrt?).  It  is  noteworthy  that  Aristotle  does  not  make 
the  distinction  between  inner  and  outer  sense  at  all.  He 
rather  avoids  the  assumption  of  an  inner  sense  co-ordinate 
with  the  outer  and  adheres  to  the  purely  conceptual  dis- 
tinction according  to  which  a common  faculty  of  sensation 
merely  shows  differing  modes  of  activity.  The  concept  of 
consciousness,  which  we  see  Aristotle  approaching  here,  is 
not  actually  developed  by  him  in  the  present  connection. 
He  does  not  approach  it  until  later,  in  his  description  of  the 
attributes  of  the  Supreme  Being,  in  the  Metaphysics.1 

Within  the  Peripatetic  school  Strato  saw  in  the  conscious- 
ness of  the  contents  of  sense-perception  a result  of  an  activ- 
ity which  was  from  the  outset  separated  from  perception. 
In  a peculiar  way  Alexander  of  Aphrodisias  returned  from 
this  to  the  older  conception,  employing  the  term  avvalaQ^m^ 
for  the  consciousness  of  perception,  a notion  which  was  des- 
tined to  remain  of  central  importance  in  the  Neo-Platonic 
1 Cf.  Chapter  VI,  1 (a),  below. 


74 


HISTORY  OF  PSYCHOLOGY 


psychology.  The  Aristotelian  doctrine  of  a common  sense, 
however,  shared  the  fate  of  many  of  the  other  conceptual 
distinctions  of  Aristotle,  and  was  interpreted  pictorially  as 
an  inner  sense,  sensus  interior,  which  was  soon  split  up,  as 
in  the  case  of  the  faculty  psychology.  Galen,  for  example, 
distinguished  three  kinds  of  inner  sense,  corresponding  to  the 
main  groups  of  phenomena  which  are  its  objects,  namely, 
imagination,  thought,  and  memory  (to  cpavraaTucov,  to 
BiavoTjTiKov f to  fxvrj ^ovucov) , thus  illustrating  the  second  point 
of  view  referred  to  above.1 

For  many  centuries  hereafter  the  inner  sense  is  reckoned 
among  the  other  mental  faculties,  losing  its  own  distinctive 
significance  more  and  more  in  the  process.  In  keeping  with 
the  terminology  of  Neo-Platonism  and  with  the  sensus  in- 
terioris  hominis,  as  Augustine  called  it,  Scotus  Erigena  in 
the  Scholastic  period  contrasted  the  inner  to  the  whole  group 
of  outer  senses.  Its  analogy  to  the  five  external  senses  is 
emphasized  still  more  by  Avicenna,  who  has  five  inner  senses 
— sensus  communis,  vis  imaginativa,  vis  cestimativa,  memo- 
ria,  and  phantasm — which  are,  like  their  external  counter- 
parts, variously  localized. 

The  opposition  between  outer  and  inner  senses  recurs  in 
Thomas  Aquinas.  The  senses  themselves  cannot  become 
aware  of  their  own  activities.  The  activities  of  the  outer 
senses  are  rather  perceived  by  a sense  different  from  them, 
an  inner  sense,  the  sensus  communis.  This  sense,  too,  is,  like 
its  corresponding  object,  physical.  It  can,  accordingly,  not 
perceive  its  own  activity,  and  we  thus  have  left  one  uncon- 
scious mental  activity  within  the  sphere  of  sense.  The  doc- 
trine of  the  inner  sense  assumes  a peculiar  relation,  more- 
over, to  that  of  “ intentional  ” or  “ mental  ” existence.  The 
notion  of  psychical  immanence  ( Einwohnung ) is  found  as 
early  as  Aristotle  in  the  doctrine  that  the  perceived  object 
1 See  pp.  71-2. 


DESCRIPTIVE  PSYCHOLOGY 


75 


exists  as  such  in  the  perceiver  and  that  the  object  thought 
of  exists  in  the  reflective  intelligence.  The  history  of  phi- 
losophy records  this  confusion  between  mental  existence  and 
actual  existence.  Philo’s  theory  of  ideas  is  founded  on  the 
notion,  while  Saint  Anselm  developed  it  into  his  proof  for  the 
existence  of  God.  Thomas  Aquinas  teaches  that  the  thing 
thought  of  is  “intentional”  in  the  thought.  Consciousness 
of  this  thought  is  rendered  possible  on  account  of  the  incorpo- 
real character  of  the  understanding,  through  the  reflection  of 
the  activities  upon  themselves.  Meanwhile,  Saint  Thomas 
denies  to  the  understanding  a plurality  of  simultaneous 
thoughts,  holding  that  such  plurality  is  possible  only  as  tem- 
poral succession.  The  perception  of  thought,  therefore,  fol- 
lows the  thought  itself  in  point  of  time.  Thomas  Aquinas 
thus  exposes  some  of  the  difficulties  in  the  accepted  doc- 
trine of  inner  perception,  difficulties  which  have  reappeared 
in  modern  psychology.  That  the  introspection  of  a mental 
process  immediately  follows  the  latter  is  a view  of  inner 
perception  held  by  many  modern  psychologists. 

This  central  problem  of  inner  perception  was  subsequently 
lost  sight  of  again.  The  treatments  of  the  number  and  clas- 
sification of  the  inner  senses  in  the  psychological  systems  of 
the  Reformation  period  are  far  removed  from  the  actual  facts 
of  consciousness.  Here  again  the  inner  sense  plays  its  part 
mainly  in  connection  with  the  reproductive  processes. 
Imagination  and  memory  play  the  leading  roles.  Associated 
with  them,  occasionally,  is  the  old  common  sense.  Distinct 
from  these  attempts  at  classification  is  the  view  of  Amerbach 
who  interprets  the  inner  sense  in  Aristotelian  fashion  as  the 
common  sense,  treating  it  as  a necessary  presupposition  to 
the  activity  of  the  outer  senses.  The  physiological  interests 
of  the  time  reflect  themselves  in  the  attempts  to  explain  the 
activity  of  the  inner  sense  by  reference  to  the  movements 
of  “nerve  spirits”  in  the  brain,  as,  for  example,  in  Casmann, 


76 


HISTORY  OF  PSYCHOLOGY 


who  well  characterized  inner  perception  as  actus  refledus 
or  as  iterata  cognitio.  The  Cartesian  definition  of  the  soul 
as  a thinking  substance  represented  inner  perception  as  be- 
longing to  the  essence  of  the  soul.  The  solution  of  the  prob- 
lem thus  suggested  was,  however,  not  turned  to  account  by 
Descartes  for  the  advance  of  empirical  psychology.  He 
rather  placed  the  outer  and  the  inner  senses  side  by  side, 
thus  preparing  the  way  for  the  sensualistic  psychology  of  a 
later  day,  in  the  sense,  for  example,  of  Hobbes,  who  called 
the  discrimination  of  sensations  itself  a sensation. 

(6)  The  Inner  Sense  as  an  Independent  Source  of  Experience 

The  classical  expression  of  the  doctrine  of  the  inner  sense 
is  found  in  John  Locke.  Locke  based  his  Essay  Concerning 
Human  Understanding  upon  the  simple  fact  that  all  our 
ideas  originate  either  in  sense-perception  or  in  reflection,  by 
which  the  soul  becomes  aware  of  its  own  activities.  Thus 
introspection  is  recognized  by  the  side  of  sense-perception 
as  an  independent  source  of  knowledge.  The  traditional 
analogy  between  the  outer  and  inner  senses  is  thus  strictly 
subordinated.  It  is  true  that  reflection  always  presupposes 
sense-perception;  at  the  same  time  Locke,  supported  by 
Cartesian  metaphysics,  asserts  the  independence  of  inner 
experience.  - 

The  epistemological  consequences  of  this  doctrine  were 
drawn  by  the  English  sensualists  Berkeley  and  Hume,  in 
both  of  whom  the  Lockian  antithesis  continued.  Berkeley 
found  the  object  of  reflection,  of  “inward  feeling,”  as  he 
called  it,  in  one’s  own  existence,  without,  however,  admitting 
the  idea  of  spirit  or  self.  The  subject  of  the  various  psy- 
chical activities  enumerated — willing,  ideation,  etc. — cannot 
be  grasped  by  reflection,  although  the  latter  can  direct  itself 
upon  these  activities  themselves.  The  result  is  a consider- 


DESCRIPTIVE  PSYCHOLOGY 


77 


able  restriction  of  the  scope  of  inner  perception,  which,  for 
the  rest,  corresponds  with  Berkeley’s  conception  of  the  soul.1 
Over  against  Locke’s  distinction  between  sense  and  reflec- 
tion Hume  placed  his  own  antithesis  of  impressions  and 
ideas.  We  now  have  impressions  of  introspection  standing 
parallel  to  impressions  of  sense-perception.  The  latter  orig- 
inate within  the  soul,  from  unknown  causes,  whereas  the 
former  originate  for  the  most  part  from  our  ideas.  Thus 
the  intellectualism  which  is  the  usual  accompaniment  of 
the  psychology  of  inner  perception  asserts  itself  in  Hume’s 
psychology  also. 

Locke’s  distinction  between  sensation  and  reflection  per- 
sisted in  English  psychology.  It  received  a variety  of  in- 
terpretations in  French  sensualism.  Condillac  disputed  the 
validity  of  reflection  as  an  independent  source  of  knowledge. 
It  originates,  rather,  in  the  specific  direction  of  the  atten- 
tion toward  ourselves,  which,  of  course,  presupposes  imagi- 
nation and  memory.  This  significant  reference  to  the  power 
of  attention  is  meanwhile  weakened  by  invoking  another 
kind  of  consciousness,  in  addition  to  reflection,  which  is  di- 
rected upon  separate  ideas.  Neither  can  we  attach  much 
importance  to  the  physiological  explanation  of  the  inner  sense 
offered  by  Bonnet,  who  ascribed  it  to  the  power  of  the  soul 
to  set  soul  fibres  in  motion  spontaneously. 

Locke’s  doctrine  of  the  inner  sense  received  its  most  im- 
portant transformation  through  Leibniz’s  celebrated  distinc- 
tion between  perception  and  apperception.  In  perception 
the  soul  merely  contains  ideas,  in  apperception  it  becomes 
conscious  of  them.  As  a knowledge  of  the  soul  of  its  inner 
states,  the  Leibnizian  apperception  bears  a fairly  close  re- 
semblance to  Locke’s  reflection.  Leibniz’s  distinction  de- 
rives a greater  significance,  however,  for  the  development 
of  the  concept  of  consciousness  in  so  far  as  it  was  later  to 

1 Cf.  p.  27. 


78 


HISTORY  OF  PSYCHOLOGY 


become  identified  with  the  distinction  between  unconscious 
and  conscious  states  of  the  soul.1 

While  Wolff  repeats  the  Leibnizian  distinctions  with  un- 
diminished emphasis  in  the  later  phases  of  the  period  of  En- 
lightenment, the  traditional  doctrine  of  the  inner  sense  re- 
appears, as  in  Baumgarten,  who  gives  a complicated  account 
of  external  and  inner  sensibility.  Among  the  eclectic  repre- 
sentatives of  the  “Popular  Psychology,”  Meiners  bases  his 
doctrine  of  the  inner  sense  upon  the  methodological  principle 
that  the  number  of  separate  organs  must  be  determined  upon 
the  basis  of  the  diversity  of  inner  experience.  The  most 
interesting  development  of  the  doctrine  of  inner  sense  in  this 
period  is  due  to  Tetens.  Since  psychical  processes  are  per- 
ceived through  the  inner  sense  in  the  same  manner  as  physi- 
cal are  perceived  through  the  outer  senses,  he  opines  that  we 
perceive  nothing  but  phenomena  in  both  cases.  The  two 
arguments  for  the  objectivity  of  the  external  world  prevalent 
in  the  theory  of  knowledge  dominant  at  the  time,  namely, 
(1)  that  sensation,  as  confused  perception,  does  not  repro- 
duce the  simplicity  of  the  outer  world,  and  (2)  that  percep- 
tion depends  upon  the  condition  of  the  sense-organ,  are  ex- 
tended by  Tetens  to  inner  perception  also.  Every  psychical 
process  may  be  composed  of  heterogeneous  elements,  which 
have  the  appearance  of  simplicity  only  for  our  apprehen- 
sion, and  for  inner  observation  the  brain  is  the  organ  upon 
which  it  depends.  For  this  reason  mere  introspection  can 
never  reach  the  elements  of  psychical  life.  These  can  be 
reached  only  by  thought,  which  operates  by  analysis  similar 
to  that  employed  by  natural  science  in  the  study  of  white 
light,  which  to  observation  appears  simple  in  character. 
These  consequences  follow  with  a certain  necessity  when 
the  doctrine  of  inner  sense  is  really  taken  seriously,  but  they 
stand  in  sharp  contradiction  to  psychological  experience  in 
1 Cf.  Chapter  VI,  2. 


DESCRIPTIVE  PSYCHOLOGY 


79 


which,  in  contradiction  to  physical,  the  elements  are  given 
concretely.1 

The  inner  sense  assumed  a many-sided  significance 
through  the  psychology  of  Kant.  Kant  distinguished  the 
inner  sense  from  apperception.  The  experiences  of  the  inner 
sense  run  their  course  in  time,  and  yield  phenomena,  as  do 
the  outer  senses.  Apperception,  on  the  other  hand,  relates 
to  the  pure  ego,  the  subject  of  all  thought  activities.  As 
object,  meanwhile,  of  inner  experience,  the  ego  knows  itself 
only  as  it  appears.  This  view  of  the  activity  of  the  inner 
sense,  which  grows  out  of  Kant’s  theory  of  knowledge,  con- 
tinues in  Kant’s  empirical  psychology,  as  set  forth  in  his 
Anthropologie,  in  a close  parallelism  between  the  inner  sense 
and  the  outer  senses.  Kant  further  distinguishes  between 
the  inner  sense  ( sensus  interims),  as  a mere  cognitive  faculty, 
and  the  inward  sense  ( inwendiger  Sinn,  sensus  interior),  the 
feeling  of  pleasantness  and  unpleasantness,  thus  denying  the 
original  relation  of  the  inner  sense  to  the  totality  of  inner 
experience.2  A more  exact  definition  limits  the  inner  sense 
to  passive  psychical  states.  It  is  not  pure  apperception,  as 
this  belongs  only  to  the  faculty  of  thought;  it  is  a conscious- 
ness of  that  which  affects  it  in  so  far  as  it  is  affected  by  its 
own  play  of  thought.  As  perception  it  is  in  this  sense  also 
subject  to  illusions,  as  when  one,  for  example,  mistakes  per- 
ceptions of  the  inner  sense  for  external  phenomena.  Here 
we  obviously  have  a reappearance  of  the  older  idea  that  the 
objects  of  the  inner  sense  are  the  processes  of  memory  and 
imagination.  The  heart  of  the  Kantian  doctrine  consists 
in  the  idea  that  the  inner  sense  substitutes  for  the  pure  or 
transcendental  ego  the  empirical  ego  with  its  variety  of  con- 
scious phenomena.  This  curious  duplication  of  the  ego  re- 
curs frequently  in  subsequent  philosophy. 

1 On  the  concept  of  psychical  element,  see  below,  Chapter  VII,  3. 

2 Anthropologie  in  pragmatischer  Hinsicht,  1798,  § 13. 


80 


HISTORY  OF  PSYCHOLOGY 


The  Kantian  doctrine  of  the  inner  sense  was  severely  criti- 
cised by  Herbart,  who  urged  that,  as  a faculty  of  introspec- 
tion, the  inner  sense  would  require  some  superior  faculty  in 
its  turn,  and  so  forth,  without  end.  Still,  the  positive  ex- 
planation of  Herbart’s,  according  to  which  one  mass  of  ideas 
observes  another,  is  still  more  seriously  burdened  with  in- 
ner impossibilities,  if  possible,  than  the  theory  which  he 
criticises. 

Schulze  controverted  the  assumption  of  an  inner  sense 
with  different  arguments  in  his  Psychologische  Anthropologie 
(1819).  The  analogy  between  the  outer  senses  and  the  in- 
ner sense  is  untenable  for  the  reason  that  the  knowledge  of  a 
perception  as  one’s  own  implies  a judgment  which  cannot 
be  ascribed  to  the  activity  of  sense.  The  interposition  of  a 
special  faculty  between  the  soul  and  perception  in  the  form 
of  an  inner  sense  can  be  defended  by  no  arguments  whatso- 
ever. If,  in  spite  of  this  criticism,  certain  representatives 
of  sensualistic  psychology  still  occasionally  maintain  the 
strict  analogy  of  the  inner  to  the  external  senses,  as  is  done 
by  Biunde  in  his  Versuch  einer  systematischen  Behandlung  der 
Psychologie  (1831)  and  by  Lelut  in  his  Physiologie  de  la 
pensee  (1862),  we  may  treat  these  utterances  as  the  echoes, 
merely,  of  a theory  which  at  this  time  and  in  this  form  has 
long  been  obsolete. 

The  merging  of  the  old  problem  of  inner  sense  in  the  more 
general  problem  of  consciousness  occurred  partly  in  connec- 
tion with  the  description  which  the  Philosophy  of  Identity 
gave  of  the  dialectical  development  of  consciousness.  One 
of  the  most  characteristic  attempts  to  make  this  develop- 
ment of  consciousness  intelligible  as  a psychological  process 
was  made  by  Ulrici,  who  held  that  inner  perception  was 
identical  with  the  beginning  of  consciousness,  and  derived 
both  from  the  distinction,  originally  unconscious,  between 
the  self  and  sensation. 


DESCRIPTIVE  PSYCHOLOGY 


81 


But  it  was  not  in  these  more  or  less  speculative  efforts 
that  the  doctrine  of  inner  sense  came  into  contact  with  the 
most  modern  tendencies  of  descriptive  psychology.  The 
question  which  came  into  the  foreground  was  the  more  gen- 
eral question  as  to  whether  pure  introspection,  which  had 
been  transmitted  historically  in  the  form  of  the  inner  sense, 
could  form  the  basis  of  an  empirical  psychology.  At  first 
these  efforts  of  empirical  psychology  lagged  decidedly  in 
spite  of  the  expositions,  so  opulent  in  impressions,  of  Beneke. 
Fortlage,  in  his  System  der  Psychologie  als  empirischer  Wis- 
senschaft  aus  der  Beobachtung  des  inneren  Sinnes  (1855),  as- 
serted that  the  observation  of  the  inner  sense  was  the  funda- 
mental source  of  experience  in  psychology.  He  held  that 
the  task  of  psychology  was  to  construct  an  empirical  science 
of  the  human  mind  founded  upon  observation  within  the 
realm  of  the  inner  sense,  and  to  arrive,  by  induction,  at  the 
ultimate  concepts  of  instinct  and  reason.1  But  in  the  actual 
construction  of  this  science  the  realm  of  “observation”  be- 
came a mere  jostling  place  of  arbitrary  assertions.  After 
laborious  expositions  of  the  functions  of  the  inner  sense,  to 
which  are  mainly  ascribed  the  attributes  of  the  external 
senses,  the  author  begins  his  “observations,”  a term  which, 
however,  is  here  merely  a synonym  for  inventive  imagina- 
tion. As  F.  A.  Lange  aptly  remarks,  it  would  be  difficult  to 
find  in  the  two  stout  volumes  a single  genuine  observation. 

The  sterility  of  such  observations  by  means  of  the  inner 
sense  demanded  its  criticism  as  a source  of  knowledge. 
Comte  had  already  made  a very  searching  and  influential 
criticism  of  it,  in  which,  however,  he  had  identified  observa- 
tion with  perception.  In  his  Cours  de  Philosophie  positive 
(1830-42),  he  declared  every  form  of  psychology  claiming 
to  discover  the  fundamental  laws  of  the  human  mind  to  be 
illusory  as  long  as  it  relied  upon  introspection.  In  spite  of 
1 System,  der  Psychologie , Vorrede,  X. 


82 


HISTORY  OF  PSYCHOLOGY 


the  fact  that  J.  S.  Mill,  in  his  account  of  Comte,  undertook 
to  defend  perception  of  psychical  phenomena  by  means  of 
direct  memory,  it  was  in  England  where  Comte’s  doctrine 
made  the  greatest  advance.  Maudsley,  too,  in  his  Physi- 
ology and  Pathology  of  Mind  (1867),  rejects  self-conscious- 
ness as  a source  of  psychological  knowledge.  In  Germany 
F.  A.  Lange  was  particularly  aggressive  in  his  criticism  of 
inner  perception,  maintaining  that  there  existed  no  clear 
line  of  demarcation  between  outer  and  inner  perception. 
The  experience  of  color  in  imagery,  for  example,  is  regarded 
as  due  to  the  observation  of  the  inner  sense.  Neverthe- 
less, there  is  no  essential  difference  between  that  and  the 
actual  sight  of  color.  Helpless  as  was  the  psychology  of 
inner  sense  against  such  criticisms,  no  result  was  reached 
regarding  the  significance  of  introspection  in  psychology. 
In  the  most  recent  developments  the  question  has  been 
considered  from  other  points  of  view,  in  connection  with  ex- 
perimental investigation,  where  the  controversy  has  centred 
around  the  competency  of  self-observation  when  regulated 
by  experiment.1 

The  doctrine  of  inner  sense  underwent  a new  development 
through  its  connection  with  certain  epistemological  problems 
raised  by  the  question  of  the  epistemological  significance  of 
the  facts  of  inner  perception. 


(c)  The  Relation  of  Inner  Sense  to  Epistemological  Problems 2 

The  connecting-link  between  the  theory  of  knowledge  and 
the  doctrine  of  inner  perception  was  the  problem  of  “evi- 
dent” or  immediately  certain  perception.  With  the  ex- 
ternal, illusory  perception  was  contrasted  inner,  evident 
perception.  Uberweg,  in  his  Logik  (1865),  ascribed  to  inner 

1 Cf.  below,  pp.  136  /. 

* Cf.  with  this  Brentano,  Psychologie  vom  emp.  Standpunkte,  p.  101. 


DESCRIPTIVE  PSYCHOLOGY 


83 


perception  the  characteristic  of  material  truth,  and  made 
this  identity  of  being  and  knowledge  the  point  of  departure 
for  his  theory  of  knowledge.  The  psychological  investiga- 
tion of  the  difference  between  external  and  inner  perception 
was  thus  demanded  by  the  theory  of  perception.  In  addi- 
tion to  this,  empirical  psychology  had  an  interest  of  its  own 
in  attempting  to  establish  its  right  to  be  regarded  as  a spe- 
cial science,  through  the  discovery  of  a realm  of  phenomena 
peculiar  to  it.  Whether  this  standpoint  is  made  necessary 
by  the  nature  of  psychical  phenomena  need  not  be  decided 
here.  In  any  case,  the  attempt  is  made  solely  on  the  basis 
of  the  facts  of  inner  perception. 

The  close  relation  to  epistemological  problems  is  further 
shown  by  the  fact  that  it  was  not  regarded  as  feasible  to 
employ  a principle  of  division  derived  from  epistemological 
presuppositions.  For  it  was  psychology  which,  as  the  funda- 
mental philosophical  discipline,  was  to  lay  the  foundation  for 
epistemological  distinctions.  The  classification  of  percep- 
tions introduced  by  Locke,  which  presupposed  the  contrast 
of  mind  and  body  as  something  given,  was  accordingly  in- 
sufficient for  the  more  rigid  demands.  In  contrast  with 
these  epistemological  determinations,  there  was  a demand 
for  a classification  of  perception  on  the  basis  of  purely  de- 
scriptive characteristics.  The  Cartesian  doubt,  which  stands 
at  the  threshold  of  the  critical  theory  of  knowledge,  prom- 
ised to  be  fruitful  for  the  solution  of  this  task.  Without  any 
presupposition  regarding  the  nature  of  psychical  events,  it 
illustrated  the  character  of  “evidence”  or  certainty  at- 
taching to  any  given  experience.  Inner  perception  is  neces- 
sarily “evident,”  while  many  experiences  derived  from  ex- 
ternal perception  render  the  ascription  of  this  characteristic 
to  external  perception  impossible.  Sir  William  Hamilton 
utilized  this  insight  for  the  determination  of  the  sphere  of 
psychical  phenomena,  characterizing  consciousness  as  im- 


84 


HISTORY  OF  PSYCHOLOGY 


mediate  or  intuitive  knowledge,  and  emphasizing  as  a pe- 
culiar feature  of  psychical  phenomena  that  they  can  be  re- 
ceived only  in  the  inner  consciousness.  The  significance  of 
this  definition,  which  appears  at  first  sight  as  a reversal 
of  the  natural  determination  of  the  act  in  accordance  with 
the  object,  lies  just  in  this  ascription  to  inner  perception 
of  the  character  of  certainty  or  evidence. 

An  attempt  to  sharpen  the  distinction  between  inner  and 
outer  perception  to  the  utmost  was  made  by  Franz  Bren- 
tano.1  Upon  the  descriptive  distinction  between  inner  and 
outer  perception  he  based  a similar  distinction  between  the 
two  corresponding  classes  of  phenomena.  Psychical  phe- 
nomena are  accordingly  such  as  can  be  perceived  only  by 
introspection,  while  physical  phenomena  are  accessible  only 
through  external  perception.  Brentano  thus  carried  through 
the  descriptive  classification  of  all  phenomena  into  physical 
and  psychical,  without  having  to  depend  upon  transcendental 
conceptions.2  The  psychology  of  the  inner  sense  had  long 
employed  the  assumption  that  physical  phenomena  are  due 
to  the  action  of  objects  upon  the  mind,  while  psychical 
phenomena  have  their  origin  in  the  perception  of  the  activi- 
ties of  the  mind.  Psychical  objects  are  now  defined  as  the 
sole  objects  of  inner  perception.  Brentano  names  still  an- 
other characteristic  of  psychical  phenomena,  their  inten- 
tional or  mental  “in-existence.”  Every  psychical  phenom- 
enon refers  to  an  object.  In  presentation  something  is 
presented,  in  judgment  something  affirmed  or  denied,  etc. 
We  have  a repetition  here,  in  a greatly  refined  form,  of 
the  Scholastic  doctrine  of  “intentional”  acts.3  Indeed, 
psychical  phenomena  are  for  Brentano  identical  with  the 
acts.  The  resulting  classification  contradicts  the  delimita- 
tion of  the  psychical  realm  given  in  the  treatment  of  sen- 

1 Op.  cit.,  pp.  131  ff.  2 See  Chapter  V,  3 ( b ),  below. 

3 See  p.  74,  above. 


DESCRIPTIVE  PSYCHOLOGY 


85 


sation  and  idea.  Brentano  regards  only  the  acts  of  sen- 
sation and  ideation  as  psychical  phenomena.  The  things 
sensed  or  represented — a color,  odor,  or  figure — are  physical 
phenomena.  The  psychology  based  upon  this  distinction 
has  recently  been  called  act  psychology.  According  to 
Brentano,  each  of  these  acts  is  accompanied  by  a con- 
sciousness of  itself.  Every  act,  accordingly,  has  two  ob- 
jects. The  primary  one  is  the  intentional  content,  the  tone, 
for  example,  in  audition;  the  secondary  one  is  the  act  itself 
as  a psychical  phenomenon,  in  this  case  as  the  phenomenon 
of  audition.  Inner  perception  thus  accompanies  every  act 
and  is  conscious  of  it  in  a threefold  way:  it  ideates  it, 
recognizes  it,  and  feels  it.  These  three  kinds  of  inner  per- 
ception also  represent  the  most  general  classification  of 
psychical  phenomena. 

The  teachings  of  Brentano,  which  were  understood  by 
many  to  represent  a species  of  Neo-Scholasticism  in  psy- 
chology, have  been  subject  to  much  controversy.  They 
have  received  their  most  adequate  criticism  at  the  hands  of 
Husserl,  who  at  the  same  time  dealt  most  successfully  with 
several  of  the  problems  of  a purely  phenomenological  analy- 
sis.1 Husserl  maintains  the  epistemological  identity  of  inner 
and  outer  perception.  It  is  true  that  there  exists  the  dis- 
tinction between  evident  and  non-evident  perception,  but 
this  distinction  does  not  coincide  with  the  distinction  be- 
tween inner  and  outer  perception.  An  example  of  the  non- 
evident  character  of  inner  perception  is  the  perception  of 
the  ego  as  the  empirical  personality.  Neither  can  the  ma- 
jority of  psychical  states  localized  in  the  body  be  perceived 
as  evident,  according  to  Husserl.  The  source  of  Brentano’s 
errors  lies  in  the  equivocal  use  of  the  term  phenomenon.  By 
the  phenomenon  Brentano  sometimes  means  the  objects  and 
attributes  which  appear,  sometimes  the  experiences  consti- 
1 Logische  Untersuchungen,  vol.  II,  1901,  pp.  7QZJJ. 


86 


HISTORY  OF  PSYCHOLOGY 


tuting  the  activity  of  appearing  (occasionally  contents  in  the 
shape  of  sensations),  and,  finally,  all  experiences  as  such. 
We  thus  have  a cross  classification  of  experiences,  as,  e.  g., 
activities  and  non-activities,  and  of  phenomenological  ob- 
jects, as,  e.  g.,  those  which  belong  to  self-consciousness  and 
those  which  do  not,  that  is,  psychical  and  physical  objects. 
He  treats,  that  is,  the  latter  as  a classification  of  experiences 
into  activities  and  non-activities,  and  furthermore  identifies 
the  contents  sensed  with  the  phenomenal  characteristics  of 
external  objects,  so  that  a general  classification  of  phenome- 
nological objects  results.  This  criticism  is  directed  toward 
one  of  the  last  offshoots  of  the  doctrine  of  the  inner  sense, 
and  illustrates  the  keenness  of  the  purely  phenomenological 
method  of  investigation  which  has  been  attained  in  present- 
day  psychology. 


CHAPTER  IV 


EXPLANATORY  PSYCHOLOGY 

If  we  were  to  arrange  the  tendencies  of  psychology  which 
have  grown  up  around  the  problems  of  explanatory  psychol- 
ogy in  the  chronological  order  in  which  the  characteristic  tools 
of  these  tendencies  became  known,  we  should  have  to  put  in 
the  first  place  the  observations  regarding  the  uniformities 
in  the  more  elementary  psychic  processes.  In  sense-percep- 
tions, in  memory,  in  impulsive  and  instinctive  activities  uni- 
formities were  observed  even  before  the  day  of  experimental 
investigation,  which  must  have  suggested  strongly  the  idea 
of  the  uniform  connection  among  psychical  phenomena. 
The  most  important  notion  available  for  explanatory  pur- 
poses was  that  of  association.  Association  psychology  ter- 
minated in  the  conception  of  psychology  as  a mechanics  of 
ideas.  A second  point  of  departure  consisted  in  the  exten- 
sion of  psychological  investigation  beyond  the  border  of  in- 
dividual psychology.  The  resulting  science  of  comparative 
psychology  was  helped  forward  especially  by  the  notion  of 
development  or  evolution.  Rut,  more  than  anything  else, 
it  was  contact  with  the  natural  sciences,  during  the  century 
just  passed,  which  furnished  explanatory  psychology  with 
new  tools  and  opened  new  paths  which  led  to  the  discovery 
of  those  psychic  laws  which  are  the  goal  of  association  psy- 
chology. 

i.  Association  Psychology 

Explanatory  psychology  has  been  said  to  supplement  de- 
scriptive psychology  in  the  respect  that  it  investigates  the 
dispositional  characteristics  of  mental  life  in  addition  to  its 

87 


88 


HISTORY  OF  PSYCHOLOGY 


t phenomenological  aspect.  Although  the  field  of  explanatory 
\ psychology  does  not  coincide  with  the  doctrine  of  psychical 
\ dispositions,  still  the  reference  to  dispositions  constitutes  one 
I of  the  main  forms  of  explanatory  psychology,  particularly  of 
association  psychology.  But  before  the  doctrine  of  associa- 
I tion  developed  into  a definite  psychological  tendency,  the 
/ concept  of  association  was  not  only  elaborated  but  the 
I notion  of  a mechanics  of  ideas  had  already  appeared.  The 
I fitful  beginnings  of  association  psychology  illustrate  how  fre- 
quently the  continuity  of  psychological  investigation  has  been 
broken.  For  a long  period  only  the  processes  of  association 
connected  with  memory  were  taken  into  account.  It  was 
only  gradually  that  the  far  broader  field  of  psychical  con- 
nections, in  which  the  concept  of  association  was  so  long  to 
dominate,  was  opened. 


(a)  The  Early  Beginnings  of  Association  Psychology 

,The  earliest  attempts  to  give  an  account  of  the  most  easily 
deserved  memory  functions  are  made  by  hylozoism.1  Par- 
menides of  Elea  accounted  for  memory  and  obliviscence  as 
he  accounted  for  all  the  rest  of  the  phenomena  of  nature,  by 
the  mixture  of  cold  and  heat.  Every  idea  presupposes  a 
certain  combination  of  these  qualities,  the  idea  disappearing 
when  the  combination  no  longer  obtains.  With  no  less 
dependence  upon  the  half-mythical,  half-metaphysical  psy- 
chology of  the  time,  Diogenes  of  Apollonia  asserts  as  the 
cause  of  forgetting  the  obstacle  which  the  body  offers  to  the 
distribution  of  air,  a belief  based  upon  the  observation  that 
one  breathes  more  freely  when  recollection  has  been  success- 
ful. Aside  from  these  beginnings,  which  in  any  case  take 


1 Cf.  with  the  following:  Bergemann,  “ Gedachtnistheoretische  Unter- 
suchungen  und  mnemotechnische  Spielereien  im  Altertum,”  Arch.  f. 
Gesch.  d.  Phil.,  VIII,  1895,  pp.  336  ff. 


EXPLANATORY  PSYCHOLOGY 


89 


into  account  only  the  negative  aspect  of  memory,  namely 
obliviscence,  the  first  attempt  to  construct  a genuine  theory 
of  memory  was  made  by  Plato.  Plato  distinguishes  the  con- 
cepts avdfivrjaK  from  The  former  signifies  the  act 

of  reproduction  of  previous  impressions,  the  latter  the  pas- 
sive persistence  of  ideas  due  to  sense-perception.1 

’Avdfj.vrjcn';  is  the  higher  faculty.  It  manifests  itself  only 
when  the  soul  in  the  knowledge  of  its  ideas  remembers  the 
impressions  of  a previous  existence.  on  the  other 

hand,  is  the  capacity  of  the  soul  associated  with  the  body  to 
retain  impressions  of  sense-perception.  It  is  said  to  resem- 
ble a piece  of  wax,  varying  in  size  according  to  the  individu- 
ality of  different  persons,  becoming  harder  and  softer,  pure 
or  defiled,  etc.2 

Aristotle  was  still  more  successful  in  his  treatment  of  the 
phenomena  of  memory,  dreaming,  and  the  processes  of  asso- 
ciation and  reproduction.  He  takes  into  consideration  not 
only  the  actual  contents  but  the  dispositional  as  well.  His 
De  Anima  treats  the  phenomenology  of  mental  life,  the  re- 
maining psychological  treatises  (the  so-called  Parva  Natu- 
ralia ) dealing  with  the  dispositional  basis.  Memory  (fj-vrifir]), 
as  the  faculty  of  psychophysical  retention,  is  distinguished 
from  recall  ( dvaiuiAvrja/ceadcu ),  which  is  made  possible 
through  the  association  of  ideas.  As  the  inner  movements 
which  run  their  course  in  a series  of  perceptions  repeat 
themselves,  the  corresponding  memory  picture  is  called  up. 
The  principle  of  association  is  either  similarity,  contrast,  or 
temporal  succession  («<£’  o/iolov  rj  ivavriov  rj  tov  crvve yyu?). 
These  laws  hold  not  only  for  single  ideas,  but  for  series  of 
ideas  as  well,  only  in  the  latter  case  they  sometimes  lose 
their  simple  character.3  For  the  derivation  of  these  laws  of 
association,  which  have  since  become  so  celebrated,  Aris- 

1 Phoedo,  73  B ff.;  Philebus,  34  B.  2 Thecetetus,  191,  C ff. 

3 De  Mem.,  2. 


90 


HISTORY  OF  PSYCHOLOGY 


totle  falls  back  upon  the  supposed  movements  of  memory- 
pictures  in  the  blood.  These  are  partly  identical  or  similar, 
partly  simultaneous  or  immediately  successive.  Now,  the 
soul  has  the  power  to  originate,  through  the  agency  of  the 
heart,  a movement  of  the  blood  which  can  revive  the  traces 
of  previous  impressions  in  the  sense-organ.  In  addition  to 
this  physiological  mechanics  of  associative  memory,  we  find 
the  beginnings  of  a general  mechanics  of  ideas,  at  least  as  far 
as  sense-perceptions  are  concerned.  The  stronger  movement 
overcomes  the  weaker.  A number  of  simultaneous  sensations 
from  a single  sense-organ  are  impossible,  as  such  sensations 
coalesce.  Sensations  from  different  sense-organs,  however, 
do  not  coalesce.  The  fusion  depends  upon  the  fact  that  the 
soul  can  in  a single  movement  sense  the  similar  more  readily 
than  the  dissimilar.  And  since  every  kind  of  sensation  im- 
plies a specific  kind  of  movement  in  the  central  organ,  the 
simultaneous  perception  of  opposite  qualities  would  necessi- 
tate simultaneous  opposite  movements.  Hence  the  simul- 
taneous occurrence  of  different  sensations  is  manifestly  im- 
possible. All  this  is  distinctly  suggestive  of  the  modern 
attempts  to  construct  a mechanics  of  ideas,  illustrating  how 
Aristotle’s  anticipations  extend  into  the  most  recent  times. 
While  English  psychology  has  been  dominated  by  his  laws 
of  association,  Herbart  revived  his  principles  of  psychical 
mechanics.1 

Ancient  psychology  did  not,  indeed,  develop  the  Aristote- 
lian tradition.  Incidentally,  Maximus  of  Tyre2  enumerates 
the  different  types  of  association.  The  following  sentence 
is  ascribed  to  him:  “As  a motion  imparted  to  one  end  of  a 
cord  traverses  the  whole  length  of  the  cord,  so  the  reason  re- 
quires only  a slight  impulse  in  order  to  recall  whole  trains 
of  ideas.”3 

1 Cf.  Siebeck,  Quaestiones  duae  de  phil.  Grcec.,  1872. 

2 Diss.,  16,  7.  3 Siebeck,  Gesch.  d.  Psychologie,  II,  p.  310. 


EXPLANATORY  PSYCHOLOGY 


91 


Plotinus,  too,  mentions  the  fundamental  idea  of  immedi- 
ate reproduction,  but  describes  memory  merely  as  a power 
of  the  soul.  Sense-perception  is  received  into  the  (pavraarL- 
kov,  where  the  images  are  stored.  The  higher  soul  then 
selects  from  the  memories  thus  stored  up  in  the  lower  soul. 

The  literature  on  mnemotechnics,  which  is  rich  in  content, 
is  distinct  testimony  to  the  interest  in  the  practical  uses  of 
memory  characteristic  of  the  time.  When  one  remembers 
that  up  to  the  time  of  Augustus  no  public  speaker  would 
dare  to  appear  in  public  with  even  the  scantiest  notes,  the 
interest  in  mnemotechnical  devices  is  easily  intelligible. 
The  beginnings  of  mnemotechnics,  wThose  discovery  is  as- 
cribed to  the  poet  Simonides,  are  legendary,  as  is  the  case 
with  similar  arts.  Most  of  the  precepts  along  this  line 
about  the  time  of  Cicero  advise  the  use  of  visual  pictures  as 
aids  to  memory.  In  order  to  have  at  one’s  command  large 
masses  of  ideas,  they  must  be  localized,  say,  in  a given  city, 
and  within  the  city,  in  the  different  buildings,  chambers, 
etc.  The  theoretical  gains  from  this  sort  of  thing  for  psy- 
chology were  small,  as  might  have  been  expected. 

In  Scholasticism  the  psychology  of  memory  was  reduced  to 
the  singular  assumption  that  the  species  of  things  are  pre- 
served by  the  soul.  It  is  in  this  sense  that  Avicenna  defined 
virtus  conservativa  et  memorialis.  More  important  are  the 
views  of  John  Buridan,  which  form  a connecting-link  between 
the  older  forms  of  psychical  mechanics  and  association  psy- 
chology. Although  still  largely  dominated  by  the  concep- 
tions of  faculty  psychology,  he  is  convinced  of  the  unity 
of  mental  life.  The  principle  of  psychical  mechanics  under- 
lying his  description  of  the  freedom  of  the  will  has  caused 
him  to  be  called  the  Herbartian  among  the  Scholastics.1 

For  a long  time  knowledge  of  associative  connections  was 
confined  to  the  phenomenon  of  memory.  The  law  of  im- 
1 Cf.  Chapter  XII,  2 (a). 


92 


HISTORY  OF  PSYCHOLOGY 


mediate  reproduction  alone  was  not  lost  to  empirical  psy- 
chology. As  a rule,  the  formulation  was  that  of  Vives: 
“Quae  simul  sunt  a phantasia  comprehensa,  si  alterutrum 
occurrat,  solet  secum  alterum  reprsesentare.”  It  was  re- 
served for  English  psychology  of  the  eighteenth  century  to 
place  the  facts  of  association  in  the  foreground  and  to  re- 
gard it  as  the  fundamental  form  of  psychical  connections. 

(b)  The  Dominance  of  the  Concept  of  Association 

The  involuntary  association  of  ideas  already  played  an 
important  role  in  the  English  psychologists  of  the  seven- 
teenth century,  Thomas  Hobbes  and  John  Locke.  It  was 
Locke,  indeed,  who  introduced  the  term  association  of  ideas 
to  designate  the  process  in  question.  Malebranche,  too,  was 
acquainted  with  the  facts  of  association,  which  he  explained 
by  the  simultaneous  occurrence  of  ideas  in  consciousness. 
Not  until  Hume  and  Hartley,  however,  in  the  middle  of 
the  eighteenth  century,  was  the  concept  of  association  made 
the  central  concept  of  explanatory  psychology. 

In  the  Treatise  of  Human  Nature  (1739-40),  Hume  enu- 
merates three  factors  which  can  give  rise  to  association : sim- 
ilarity, immediate  spatial  and  temporal  connection,  and  cause 
and  effect;  and  in  his  Dissertation  on  the  Passions  (1770)  he 
defines  association  generally  as  the  principle  of  facilitated 
transition  from  one  idea  to  another.  In  accordance  with  the 
principles  of  combination  of  simple  ideas  arise  those  complex 
ideas  “which  are  the  common  subjects  of  our  thoughts  and 
reasoning”:  relations,  modes,  and  substances.  While  Hume 
based  his  theory  of  association  upon  psychological  experience, 
he  utilized  it  for  his  empirical  theory  of  knowledge,  one  of 
the  main  features  of  which  is  his  bold  reduction  of  the  con- 
sciousness of  reality  to  associatively  conditioned  relations. 
As  is  well  known,  Hume  explains  the  different  kinds  of  belief, 


EXPLANATORY  PSYCHOLOGY 


93 


particularly  the  belief  in  the  reality  of  the  external  world,  by 
the  force  and  vivacity  of  the  corresponding  idea.  In  conse- 
quence of  the  principle  of  association,  the  force  and  vivacity 
which  belong  to  a given  impression  communicate  themselves 
to  those  related  to  it.  In  addition  to  the  reality  of  sense-per- 
ception, there  is  also  the  reality  of  ideas  of  memory,  which 
are  distinguished  from  ideas  of  fancy  by  the  necessary 
connections  existing  among  the  different  perceptions,  and, 
finally,  the  reality  of  judgment.1  Thus,  in  virtue  of  the  prin- 
ciple of  associative  connections,  the  various  kinds  of  con- 
sciousness of  reality  are  reduced  to  the  same  ultimate  fact 
of  consciousness.  The  connection  with  the  theory  of  knowl- 
edge has  stimulated  an  interest  in  the  psychological  inves- 
tigation of  the  consciousness  of  reality  which  has  been  un- 
interrupted, and  the  modern  Neo-Humeanism,  which  finds 
an  ally  in  psychologism,  occasionally  approaches  again  the 
Humean  solution  of  the  problem. 

Falling  in  with  the  ideas  of  the  time,  Hartley  connected 
the  doctrine  of  association  with  the  hypothesis  of  nerve  vi- 
bration and  attempted  to  establish  a psychophysical  theory 
of  association.  He  even  tried  to  represent  brain  changes 
pictorially,  thus  returning  to  the  older  point  of  view  of  the 
school  of  Malebranche,  a representative  of  which,  Theodore 
van  Craanen,  had  made  graphic  representations  of  material 
ideas.2  We  are  here  reminded  of  the  teachings  of  Descartes, 
who  had  described  ideas  rerum  materialium  as  brain  impres- 
sions produced  by  movements  within  the  body  which  are 
sensed  by  the  soul  in  perception.  Hartley  also  has  capital 
analyses  here  and  there  of  complex  mental  processes,  which 
employ  distinctly  the  fundamental  principles  of  association 
psychology  according  to  which  complex  phenomena  are  ex- 
plained by  the  association  of  their  component  elements.  In 

1 Treatise  of  Human  Nature,  bk.  I,  part  III,  sects.  VIII  and  IX. 

2 Tractalus  de  homine,  London,  1689. 


94 


HISTORY  OF  PSYCHOLOGY 


this  sense  he  analyzed  the  process  of  speech,  for  example, 
into  four  component  parts:  auditory  impressions,  move- 
ments of  the  vocal  organs,  visual  impressions  of  the  writ- 
ten characters,  and,  finally,  movements  of  the  hand  in 
writing.1 

The  physiological  hypotheses  of  Hartley  were  further  util- 
ized by  Charles  Bonnet,2  who,  in  his  efforts  to  exhibit  the 
physiological  conditions  of  mental  life,  abandoned  himself 
wholly  to  the  speculations  of  the  “nerve-fibre  psychology.”3 
Testimony  to  the  many-sided  psychological  interests  of  this 
writer  is  his  fondness  for  the  study  of  bee  life,  which  has 
ever  been  a puzzling  problem  for  psychology.4  Bonnet’s 
theory  of  association  can  be  summed  up  as  follows:  Nerve- 
fibres  excited  simultaneously  or  in  immediate  succession, 
and  those  which  are  spatially  contiguous,  are  connected  in 
such  a manner  that  a repeated  motion  of  any  fibre  gives 
rise  to  a sympathetic  movement  in  fibres  connected  with  it. 
Even  remembered  ideas  owe  their  origin  to  specific  move- 
ments of  fibres.  The  impression,  however,  made  upon  the 
soul  by  fibres  excited  for  the  first  time  is  different  from  that 
produced  by  subsequent  excitations.  Hence  the  difference 
between  imagery  and  sense-perception.  Thus  the  old  doc- 
trine of  material  ideas,  which  has  passed  through  a whole 
series  of  metamorphoses,  reappears  again.  Traces  of  the 
doctrine  are  also  seen  in  the  recent  assumption  of  memory 
cells  in  Meynert  and  Ziehen. 

In  Germany  the  influence  of  the  doctrine  of  association  is 
seen  partly  in  the  Wolffian  school,  partly  in  the  recent  at- 
tempts to  treat  psychological  problems  in  relation  to  nerve 
physiology  and  the  physiology  of  the  senses.  Like  the  nat- 

1 Observations  on  Man,  his  Frame,  his  Duties,  his  Expectations,  1749. 

2 Essai  analytique  sur  les  facultes  de  I’dme,  1760. 

3 Cf.  Speck,  “Bonnets  Einwirkung  auf  die  deutsche  Psychologie  des 
vorigen  Jahrhunderts,”  Archiv  f.  Gesch.  d.  Phil.,  X,  1897,  pp.  504  ff. 

4 Bonnet,  CEuvres  d’histoire  naturelle,  1779-83. 


EXPLANATORY  PSYCHOLOGY 


95 


ural  sciences,  it  found  support  in  the  growing  interest  in 
pathological  phenomena.  It  shared  with  faculty  psychology 
and  the  psychology  of  the  inner  sense  the  results  of  that  pe- 
culiar species  of  introspection  to  which  the  psychological 
periodicals  of  the  second  half  of  the  eighteenth  century,  now 
mostly  forgotten,  bear  instructive  testimony. 

Once  the  thought  was  grasped  that  so  important  a mental 
process  as  association  could  be  explained  by  the  mechanism 
of  the  nervous  system,  it  was  an  easy  step  to  extend  this 
method  to  the  whole  field  of  mental  phenomena.  The  ten- 
dency found  a response  in  the  psychophysical  materialism  of 
the  French  Enlightenment.  Thus  arose  a physiological  psy- 
chology which  sometimes  tended  to  approach  pure  material- 
ism, sometimes  recognized  the  independence  of  the  realm 
of  inner  sense,  but  sought  to  bring  its  phenomena  into  rela- 
tion with  physiological  processes.  M.  Hissmann  aided  in  the 
dissemination  of  this  tendency  through  his  translation  of 
Hartley,  published  in  his  own  periodical  (1778  ff.).  In  his 
Psychologische  Versuche  he  makes  the  dependence  of  mental 
phenomena  upon  the  brain  his  starting-point.  The  nervous 
system  and  the  brain  are  conscious,  just  as  other  bodies  are 
electric  or  magnetic.  It  behooves  the  psychologist,  there- 
fore, to  give  attention  to  physiology,  and  especially  to  the 
anatomy  of  the  brain.  To  the  two  general  laws  of  associa- 
tion, the  laws  of  coexistence  and  of  similarity,  he  added  the 
law  of  the  physical  relation  of  the  inner  organs.  Certain 
groups  of  ideas  are  to  be  explained  by  the  natural  relations 
of  their  corresponding  bodily  organs.  A significant  applica- 
tion of  these  points  of  view  to  the  theory  of  knowledge  was 
made  by  J.  C.  Lossius,1  who  attempted  to  construct  a 
mechanics  of  the  thought  processes.  Thoughts  are  composed 
of  sensations:  they  become  truths  by  a process  of  comparison 
with  other  thoughts,  which,  in  turn,  depend  upon  brain 
1 Physische  Ursachen  des  Wahren,  1775. 


96 


HISTORY  OF  PSYCHOLOGY 


movements.  Truth  as  distinguished  from  contradiction  is, 
therefore,  to  be  explained  by  harmonious  vibrations  of  nerve- 
fibres.  Lossius  thus  approaches  the  form  of  empirical  the- 
ory of  knowledge  which  developed  in  the  nineteenth  century 
under  the  name  of  psychologism.  The  law  of  contradiction, 
for  example,  would  be  explained  by  him  as  follows : “ Our  in- 
ability to  conceive  simultaneously  a triangle  and  a quad- 
rangle is  due  to  the  fact  that  the  movements  of  different 
nerve-fibres  inhibit  each  other.”  It  is  only  necessary  to 
substitute  psychical  thought  processes  for  the  hypothetical 
nerve  vibrations  with  which  Lossius  operates  in  order  to  get 
a pretty  close  approximation  to  the  point  of  view  of  psy- 
chologism, as  developed  since  the  time  of  John  Stuart  Mill.1 

A mediating  point  of  view  was  taken  by  K.  F.  von  Irwing,2 
who  maintained  that  the  physiological  basis  of  sensations 
and  of  their  connections  was  to  be  found  in  the  connections 
among  nerve-fibres  within  the  brain.  The  human  mind  is 
distinguished  from  the  animal  mind,  which  is  wholly  depen- 
dent upon  this  structural  basis,  by  the  possession  of  self- 
active understanding.  Irwing  is  more  original  in  his  criti- 
cism of  Bonnet’s  naively  pictorial  theory  of  memory,  and  he 
occasionally  has  good  observations  in  his  more  purely  de- 
scriptive passages,  as  in  his  comparison  of  previously  experi- 
enced secondary  ideas  with  present  ones. 

The  most  important  psychologist  of  this  group  is  E.  Platt- 
ner,3  whose  treatment  of  sense-perception  is  particularly  de- 
tailed. To  the  external  impression  of  the  peripheral  nerve- 
endings  is  added  an  inner  impression  in  the  “nerve  spirits” 
of  the  brain.  It  is  not  until  attention  is  turned  upon  this 
that  the  understanding  recognizes  ideas.  The  preservation 
of  ideas  he  originally  conceived  after  the  fashion  of  the  per- 
sistence of  material  ideas,  later  attributing  it  to  facilitation 

1 Cf.  Chapter  V,  3 (a),  below. 

2 Erfahrungen  und  Untersuchungen  iiber  den  Menschen,  1778. 

3 PhUosophische  Aphorismen,  1776-82. 


EXPLANATORY  PSYCHOLOGY 


97 


of  nervous  action.  The  combinations  of  the  ideas  of  im- 
agination are  accounted  for  by  the  participation  of  active 
thought,  as  well  as  of  the  laws  of  association. 

Another  tendency  of  the  day  sought  to  interpret  the  facts 
of  association  in  a purely  psychological  manner.  Marcus 
Herz,  who  was  acquainted  with  Kant  through  correspon- 
dence, not  only  outlined 1 a theory  of  association  but  also  sug- 
gested a general  mechanics  of  ideas.  True  to  the  intellectu- 
alism  of  his  time,  he  viewed  the  activity  of  the  ego  as  a form 
of  ideation.  Each  idea  has  a focal  point  of  greatest  vivacity. 
A definite  interval  always  elapses  between  the  complete  ap- 
prehension of  an  idea  and  the  direction  of  the  attention  to 
its  successor.  The  length  of  the  interval  depends  partly  upon 
the  structural  content  of  the  separate  ideas,  partly  upon  their 
mutual  relation,  i.  e.,  their  identity  or  similarity,  difference  or 
contrast,  etc.  The  law  of  association,  however,  is  not  a pri- 
mary law.  It  rather  depends  upon  the  law  that  the  repe- 
tition of  an  activity  occurs  with  minimized  effort  and  hence 
with  a lessened  interval.  A matter  deserving  of  special 
recognition  is  his  vigorous  denial  of  the  doctrine  of  the  unin- 
terrupted presence  of  ideas.  His  concept  of  facilitation  ap- 
proximates to  some  extent  the  modern  notion  of  psychical 
disposition. 

It  is  true  that  J.  D.  Iloffbauer’s  Grundriss  der  Erfahrungs- 
lehre  (1794)  is  still  based  upon  the  old  principles  of  faculty 
psychology  and  the  psychology  of  the  inner  sense.  Never- 
theless, all  the  objects  of  the  inner  sense  are  shown  to  be 
subject  to  the  law  of  association  by  the  fact  that  the  re- 
producing and  the  reproduced  ideas  are  already  connected 
within  a single  total  idea.  Against  such  a unitary  law  of 
association  and  its  derivation  from  the  concept  of  imagina- 
tion L.  H.  Jakob  contended  in  his  Grundriss  der  Erfahrungs- 
seelenlehre  (1791),  a work  distinguished  for  its  clear, 
1 Versuch  uber  den  Schwindel,  1791. 


98 


HISTORY  OF  PSYCHOLOGY 


methodical  formulations.  In  spite  of  many  interesting  re- 
marks on  the  conditions  of  sensation,  its  dependence  upon 
the  receptivity  of  the  sense-organs,  and  the  like,  we  find 
many  concessions  to  the  old  faculty  psychology.1 

The  one  work  of  this  period  which  has  been  most  successful 
in  escaping  general  oblivion  is  the  Versuch  iiber  die  Einbil- 
dungskraft,  by  G.  E.  Maass,  who  represents  a transition  be- 
tween the  empirical  psychology  of  the  eighteenth  century 
and  the  idealistic  psychology  of  Romanticism.  The  defi- 
nition which  he  offers  of  imagination  as  that  active  faculty 
of  the  soul  which  compares  the  parts  of  a complex  object 
shows  the  influence  of  the  great  thinker  who  dominated  all 
his  contemporaries.  Imagination  underlies  the  law  of  asso- 
ciation both  in  its  three  well-known  forms  and  in  its  fourth 
form,  the  law  of  revival,  which  states  that  among  “ a number 
of  ideas  the  most  prominent  idea  is  revived.”  Prominence 
here  is  determined  by  clearness.  Maass  thus  suggests  the 
point  of  view,  common  to  many  of  his  contemporaries,  of 
psychical  mechanics,  a form  developed  particularly  during 
the  nineteenth  century. 

In  this  versatile  period  of  the  Enlightenment  we  find  also 
the  first  attempts  to  apply  the  law  of  association  to  aesthetics, 
attempts  based  upon  the  significance  of  association  for  the 
affective  life,  with  which  writers  had  long  been  acquainted. 
As  a famous  historical  illustration  of  the  recognition  of  the 
associative  connections  between  sensations  and  feelings  may 
be  cited  the  curious  edict  issued  in  Paris  forbidding  the  play- 
ing of  the  Alpine  cowherd’s  melody  so  long  as  Swiss  mer- 
cenaries served  in  the  French  army,  on  the  ground  that  it 
produced  homesickness.2  The  principle  of  association  which 

1 Cf.  the  particularly  happy  description  of  these  efforts  in  M.  Dessoir, 
op.  cit.,  pp.  232  ff. 

2 Homesickness  ( Heimweh ) is  the  translation  of  nostalgia.  The 
physician  J.  J.  Scheuchzer  published  a work,  De  nostalgia  Helvetiorum, 
in  1731. 


EXPLANATORY  PSYCHOLOGY 


99 


Fechner  introduced  into  aesthetics  is  partly  anticipated  in 
Henry  Home  in  the  form  of  the  law  that  the  pleasantness  of 
a given  object  tends  to  spread  to  other  objects.1  The  tra- 
ditional principle  of  unity  within  variety  is  also  explained  by 
association.  The  succession  of  ideas  which  must  occur  at  a 
certain  rate  presupposes  a corresponding  interchange  among 
the  ideas,  which  is  partly  facilitated  by  association,  partly 
restricted  to  a determinate  set  of  relationships.  The  prin- 
cipal function  of  association  thus  consists  in  binding  to- 
gether the  greatest  possible  number  of  ideas  into  the  clos- 
est possible  relationship.  A similar  theory  of  association  is 
formed  in  Diderot.  His  definition  of  the  beautiful,  “Beau 
est  tout  ce  qui  reveille  en  nous  l’idee  des  rapports,”  seems 
to  have  been  formed  with  the  principle  of  association  in 
mind. 

The  fusion  of  both  tendencies  is  seen  in  the  aesthetics  of 
Herder,  in  which  association  also  plays  an  important  role. 
The  psychological  formulation  of  aesthetic  problems  appears 
in  clearer  form  in  his  older  studies  and  sketches  on  Plastik, 
and  in  the  torso  of  his  fourth  Kritische  Waldchen,  than  in  his 
earlier  and  more  polemical  Kalligone.  The  variety  of  indi- 
vidual taste  as  well  as  the  mutual  influence  of  the  experience 
gained  from  the  various  senses,  seen  most  conspicuously 
in  the  senses  of  sight  and  touch,  everywhere  emphasizes 
the  significance  of  association.  It  is  true  that  the  prob- 
lem of  the  relation  of  form  and  content  was  derived  from 
the  rationalistic  aesthetics  of  Baumgarten.  Nevertheless,  the 
harmony  of  form  and  content  shown  in  the  aesthetic  object  is 
for  Herder  a fact  which  has  definite  psychological  conditions ; 
it  is  a special  result  of  association.  Herder  anticipates  mod- 
ern aesthetics  in  still  another  way.  If  the  spirit  of  a work 

1 Elements  of  Criticism,  1762,  p.  66.  Cf.  A.  Tumarkin,  “Das  Associa- 
tionsprinzip  in  der  Geschichte  der  Asthetik,”  Arch.  f.  Gesch.  d.  Phil., 
XII,  1899,  p.  257. 


100 


HISTORY  OF  PSYCHOLOGY 


of  art  and  of  its  forms  is  to  make  its  appeal,  it  must  be 
through  an  act  of  sympathy,  an  inner  affinity,  in  virtue  of 
which  we  can  transport  ourselves  into  these  forms,  and  thus 
simulate  their  psychic  life.1  Elsewhere  he  writes  that  we 
can  appreciate  the  human  form  because  we  ourselves  live  a 
bodily  life,  and  can  thus  share  the  life  of  the  spirit  which 
the  body  reveals.2  We  have  here  an  anticipation  of  Lotze’s 
symbolic  beauty,  in  so  far  as  aesthetic  products  appear  to 
us  as  symbols  of  psychic  states  experienced  by  ourselves. 
These  reflections,  finally,  suggest  the  notion  of  empathy 
(Einfiihlung) , a conception  derived  from  the  philosophy  of 
Romanticism,  which  has  become  a concept  of  fundamental 
importance  in  aesthetics  through  the  discussions  of  Lipps. 

Association  psychology  shared  the  fate  of  many  other  in- 
tellectual tendencies  of  the  eighteenth  century  in  being 
obscured  by  the  philosophical  movement  originated  by 
Kant  and  developing  into  the  philosophy  of  Romanticism. 
By  the  side  of  the  mighty  problems  which  emerged  in  this 
movement,  the  problem  of  the  theory  of  knowledge,  the  prob- 
lem of  development  in  nature  and  history,  the  attempts 
of  the  psychology  of  the  Enlightenment  to  add  to  the  store 
of  human  knowledge,  often  motived,  as  they  were,  by  prac- 
tical interests,  must  have  lost  their  significance.  Associa- 
tion psychology  was  perhaps  more  successful  in  surviving 
the  attacks  of  the  Critical  Philosophy  and  the  storm  of  Ro- 
manticism. The  tradition  was  continued  in  England,  the 
home  of  associationism,  occasionally  even  throwing  off  the 
influence  of  intellectualism,  as  in  the  case  of  Brown,3  who 
extended  the  processes  of  association  to  the  realm  of  the 
feelings.  Brown  further  sought  to  unify  the  laws  of  associa- 
tion, and  his  assumption  that  a principle  of  unity  was  to  be 

1 Plastik,  and  the  accompanying  studies,  VIII,  pp.  56/.,  91,  153/. 

2 Kalligone,  1800,  XXII,  p.  173. 

3 Lectures  on  the  Philosophy  of  the  Human  Mind , 1820. 


EXPLANATORY  PSYCHOLOGY 


101 


found  in  the  coexistence  of  ideas  with  a common  feeling 
again  shows  the  significance  of  the  feelings  for  the  processes 
of  association.  Among  the  Scottish  philosophers  Sir  Wil- 
liam Hamilton,  although  still  under  the  influence  of  faculty 
psychology,  gave  a description  of  the  association  processes, 
which  he  treated  as  an  illustration  of  the  law  of  redintegra- 
tion, the  law  that  ideas  which  have  formed  parts  of  a sys- 
tem tend  to  recall  each  other.  In  closer  connection  with 
English  empiricism  of  the  eighteenth  century,  the  funda- 
mental outlines  of  associationism  were  drawn  by  James  Mill 
(1773-1836),  who  ranks  as  one  of  the  most  important  of  the 
founders  of  the  new  association  psychology.  The  only  class 
of  psychical  facts  recognized  by  Mill  is  sensation,  the  only 
law  recognized  is  the  law  of  association,  of  which  association 
by  contiguity  is  the  most  general  form. 

Associationism  owes  its  traditional  logical  formulation  to 
John  Stuart  Mill,  who  announced,  in  his  System  of  Logic 
(1843),  a psychological  law  which  was  to  serve  as  a universal 
explanation  of  the  connection  among  states  of  conscious- 
ness.1 The  main  classes  of  states  of  consciousness  are 
thoughts,  feelings,  will-acts,  and  sensations.  The  classifi- 
cation is  indeed  unsatisfactory  enough.  What  is  important 
is  the  claim  that  it  is  the  laws  according  to  which  states  of 
consciousness  succeed  each  other  which  form  the  proper 
subject-matter  of  scientific  psychology.  The  usual  laws  of 
association  are  cited  as  illustrations  of  the  process  in  ques- 
tion, and  they  are  given  a fictitious  significance  by  their  sug- 
gested analogy  to  the  law  of  gravitation.  An  example  of 
such  a general  law  is  the  law  that  any  psychical  impression, 
no  matter  what  its  cause,  will  reappear  in  a similar  though 
weakened  form  when  the  original  cause  is  no  longer  present. 
Mill  thus  calls  attention  for  the  first  time  to  the  so-called 
symbolic  function  of  memory  images,  which  has  been  treated 
1 Bk.  VI,  Chap.  IV. 


102 


HISTORY  OF  PSYCHOLOGY 


by  a number  of  modern  psychologists,  H.  Cornelius,  for  ex- 
ample, as  an  ultimate  and  inexplicable  fact  of  consciousness. 

The  attempt  to  unify  the  doctrine  of  association  eventu- 
ally left  standing  only  two  fundamental  forms  of  the  process: 
inner  association,  for  which  similarity  and  contrast  are  the 
two  most  important  qualitative  characteristics  of  the  con- 
tents associated,  and  outer  association,  which  results  from 
the  empirical  connections  of  these  contents  within  conscious- 
ness. The  demand  for  unification  was  also  met  by  Alex- 
ander Bain,  from  whose  first  important  psychological  work, 
The  Senses  and  the  Intellect  (1855),  dates  an  increasing  in- 
terest in  the  association  theory.  He  reduced  the  various 
forms  of  association  to  association  by  similarity  and  contigu- 
ity, a contrast  which  resembles  that  between  inner  and  outer 
association.  Aside  from  these  simple  forms  of  association, 
there  are  also  complex  forms,  and,  within  the  realm  of  im- 
agination, so-called  constructive  associations.  The  rigid 
scheme  of  association  is  thus  expanded  so  as  to  include  all 
forms  of  psychical  phenomena  from  the  most  simple  mental 
connection  to  voluntary  actions.  If  the  law  of  self-preser- 
vation is  added,  you  can  take  even  a voluntary  action  and 
reduce  it  completely  to  associations  between  spontaneous 
actions  and  the  chance  agency  of  pleasure. 

The  tendency  toward  the  unification  of  the  associative 
processes  has  recently  given  rise  to  the  singular  controversy 
over  the  question  whether  in  the  last  resort  association  by 
similarity  or  association  by  contiguity  is  to  be  regarded  as 
the  primary  form.  In  the  discussion  between  Hoffding  and 
Lehmann  one  of  the  most  instructive  examples  was  the 
association,  Alexander  the  Great-  Frederick  the  Great,  which 
Hoffding  ascribed  to  similarity  between  the  two  generals, 
while  Lehmann1  regarded  the  case  as  one  of  association 
by  contiguity  due  to  the  common  predicate,  “the  great.” 

1 Wundt,  Phil.  Studien,  V,  pp.  96  ff.;  VII,  pp.  169  ff VIII,  pp.  86  ff. 


EXPLANATORY  PSYCHOLOGY  103 

The  measure  of  truth  in  both  positions  well  illustrates  the 
futility  of  the  whole  question. 

The  whole  theory  of  association  was  thought  out  to  its 
ultimate  consequences  by  Herbert  Spencer.  His  elements 
of  psychical  life  or  “units  of  feeling”  are  psychical  atoms 
constituting  an  unknowable  spiritual  substance.  The  con- 
nections among  these  simple  contents  of  consciousness  are 
formed  in  accordance  with  the  fundamental  laws  of  associa- 
tion that  every  “feeling”  as  well  as  every  relation  between 
“feelings”  associates  itself  with  its  like  in  the  past  experi- 
ence of  the  individual.  There  is  evidently  a close  relation 
between  this  process  and  the  physiological  processes  of  ha- 
bituation, and  Spencer  thus  returns,  in  a sense,  only  in  a 
greater  measure,  to  the  physiological  point  of  view  of  Hart- 
ley. But  Spencer  belongs  to  a new  epoch.  His  psychol- 
ogy is  based  upon  the  notion  of  development  or  evolution 
and  thus  connects  itself  with  the  more  recent  tendencies 
of  psychology  in  Germany. 

Psychology  was  not  directly  influenced  by  the  ideas  of 
Romanticism  so  much  as  were  the  other  mental  sciences. 
Its  development  rather  occurred  in  connection  with  the 
thinker  who,  alone  among  his  idealistic  contemporaries, 
sought  to  found  the  science  of  psychology  anew — I mean 
Herbart.  In  his  hands  psychology  becomes  a science, 
striving  to  express  psychical  uniformities  by  the  aid  of  an 
exact  scientific  terminology.  Going  far  beyond  the  facts 
and  forms  of  association,  he  seeks  to  restate  these  in  terms 
of  a science  of  psychical  mechanics. 

2.  Psychology  as  a Mechanics  of  Ideas 

At  the  time  of  Herbart  German  psychology  had  lost  itself 
in  the  ideas  of  Romanticism.  The  most  important  psycho- 
logical idea  of  the  time,  if  we  abstract  from  the  metaphysical 

/ 

I 


104  HISTORY  OF  PSYCHOLOGY 

background,  was  the  construction  of  the  history  of  conscious- 
ness out  of  the  concept  and  the  fundamental  facts  of  con- 
sciousness.1 Herbart  himself  is,  perhaps,  more  representa- 
tive of  his  time  than  he  is  often  thought  to  be,  since  he  based 
his  psychology  largely  upon  metaphysics.  In  his  observa- 
tions on  the  history  of  psychology  he  discussed  the  relation  of 
his  own  point  of  view  with  those  of  a number  of  his  prede- 
cessors and  his  contemporaries.2  He  defends  the  rational 
I psychology  of  Leibniz  against  the  attacks  of  Kant.  He 
I asserts  his  own  point  of  departure  to  be  the  psychology  of 
I Fichte,  whose  merit  it  was  to  expose  the  contradictions  in- 
volved in  the  concept  of  the  ego.  Among  his  contemporaries 
Fries  had,  according  to  Herbart,  most  conclusively  proved 
the  shortcoming  of  the  Kantian  psychology,  while  Weiss 
\ had  based  psychology  upon  a dynamic  conception  of  nature. 
\ The  metaphysical  presuppositions  upon  which  he  founded 
his  own  psychology  assigned  him  a position  from  which  he 
never  advanced.  He  is  left  standing  at  the  beginning  of 
the  nineteenth  century  much  as  Leibniz  was  left  standing 
at  the  beginning  of  the  preceding  one.3  Nevertheless,  it  is 
the  merit  of  Herbart  to  have  introduced  into  explanatory 
psychology  the  concept  of  a mechanics  of  ideas  based  upon 
the  valuable  conception  of  psychical  uniformity.  The  soul 
which,  on  account  of  the  unity  of  consciousness,  must  be 
thought  of  as  a simple,  real  being,  contains,  as  forms  of  its 
self-preservation,  presentations  or  ideas.  Similar  or  dis- 
parate ideas  fuse  with  one  another;  opposite  or  partially 
opposite  ideas  inhibit  one  another  in  proportion  to  their 
opposition.  Inhibition  has  the  effect  of  diminishing  the 
intensity  of  ideas.  The  relations  involved  in  the  process 
of  inhibition,  moreover,  are  amenable  to  exact  mathemati- 
cal treatment.  As  a “statics  of  ideas”  mathematical  psy- 

1 Cf.  p.  29.  2 Werke,  Hartenstein  ed.,  V,  pp.  251  ff. 

3 Cf.  p.  27. 


EXPLANATORY  PSYCHOLOGY 


105 


ckology  seeks  to  ascertain  the  terminal  condition  in  which 
ideas  are  in  equilibrium;  as  a mechanics  of  ideas  it  seeks 
to  determine  their  intensities  during  their  course. 

A statics  of  ideas  takes  as  its  point  of  departure  reflections 
such  as  the  following:  If  we  start  with  two  opposite  ideas 
of  equal  intensity,  the  intensity  of  each  will,  in  consequence 
of  the  resulting  inhibition,  be  diminished  to  one  half  of  its 
original  intensity.  The  inhibition  sum  is  in  this  case  equal 
to  the  total  inhibition  which  distributes  itself  over  the  two 
ideas.  In  the  case  of  the  unequal  intensity  of  the  two  ideas, 
a and  b (a  > b),  it  is  sufficient  that  a quantity,  b,  be  inhibited 
in  both.  Now  an  inhibition  sum,  b,  will  distribute  itself 
over  both  ideas  in  such  a manner  that  each  will  suffer  in- 
hibition the  less,  the  greater  the  force  which  it  possesses. 

J) 2 dJ) 

The  inhibition  of  a will  therefore  be ; of  b,  . By 

cl  -f-  b ci  -f-  b 

simple  subtraction  the  intensity  of  the  remaining  ideas  can 
be  determined.1  But  Herbart  has  still  not  arrived  at  the 
fact  of  the  threshold  of  consciousness.  The  condition  under 
which  an  idea  would  entirely  disappear  below  the  threshold 

of  consciousness  would  be  & <~.  = 0,  whence  b=0.  Only 

off-  o 

when  three  ideas,  a,  b,  c (a>b>  c),  occur  can  the  weakest 
disappear  below  the  threshold,  under  the  auxiliary  assump- 
tion that  the  inhibition  sum  is  now  b + c. 

The  fundamental  equation  for  the  mechanics  of  ideas  is 
also  derived  from  a consideration  of  the  inhibition  sum.2 
In  their  original  state  ideas  are  entirely  uninhibited  and 
constitute  an  inhibition  sum.  As  the  inhibition  sum  di- 
minishes, the  movement  of  ideas  begins.  If  the  inhibition 
sum  is  S,  and  <r  the  inhibited  quantity  after  the  expiration 
of  a time,  t,  then 

(, S — cr)dt=d<r . 

1 Psychologie  als  Wissenschaft,  1824-5,  §§  41 ff.  2 Op.  cit.,  § 74. 


106 


HISTORY  OF  PSYCHOLOGY 


While  in  the  mechanics  of  bodies  the  force  determines 
only  the  differential  of  the  rate  of  motion,  here  it  determines 
the  very  rate  itself.  From  the  integration  of  the  equation 
follows 


t=  log 


Const 


Since  when  t=0  also  cr=0,  const  = S;  and  for  the  inhibited 
quantity  we  get 

cr=  S^l—er1). 

In  this  equation  is  contained  the  law  according  to  which  the 
actually  inhibited  quantity  of  any  inhibition  sum,  S,  increases 
in  a time,  t.  By  an  analogous  calculation  we  can  determine 
the  time  for  the  rise  of  ideas.1  If  <]>  stands  for  receptivity, 
and  if  within  a time,  t,  a quantity,  z,  of  presentation  is  pro- 
duced, then  the  receptivity  at  the  expiration  of  t is  only 
(f> — z.  If  the  force  of  a disturbance,  say,  a brightness,  is  /3, 
we  have  the  equation 

/3(<j>—z)dt  = dz,  whence 

z = 4>(l  —erpt). 

To  this  equation  corresponds,  in  addition  to  the  general 
principles  of  metaphysics,  the  known  fact  “ that,  first,  every 
perception  requires  a short  interval  of  time  if  the  resulting 
idea  is  to  attain  to  a finite  degree  of  strength  among  other 
ideas;  secondly,  that  a perception  prolonged  beyond  a cer- 
tain time  produces  no  increase  in  the  resulting  strength  of 
the  idea.”  The  passage  clearly  suggests  the  problem  con- 
nected with  the  increase  of  the  sensation  stimulus  with 
which  subsequent  sense  psychology  was  to  occupy  itself, 
and,  indeed,  the  ascending  curves  obtained  by  empirical 
measurements  occasionally  approach  the  fundamental  form 
deduced  by  Herbart.  Up  to  a certain  point,  too,  mathe- 
matical psychology  connected  itself  again  with  the  Her- 
bartian  problem  of  the  statics  of  ideas  in  subjecting  the  prob- 

1 Op.  cit.,  § 94. 


EXPLANATORY  PSYCHOLOGY 


107 


lems  of  the  distribution  of  degree  of  clearness  in  conscious- 
ness, and  of  the  inhibition  or  assimilative  interaction  of 
ideas,  to  experiment.  Nevertheless,  the  passages  in  Herbart’s 
psychology  in  which  he  shows  signs  of  abandoning  his 
imaginary  mechanics  of  ideas  for  actual  psychological  ex- 
perience are  of  rare  occurrence.  Indeed,  it  is  merely  a frac- 
tion of  this  experience,  a limited  range  of  certain  intellectual 
processes,  with  which  his  psychology  deals.  Following  out 
his  presuppositions  to  their  logical  conclusions,  Herbart 
intellectualized  mental  life  to  a degree  nowhere  else  reached 
in  the  history  of  psychology. 

The  Herbartian  tradition  was  continued  by  a small  number 
of  disciples  for  a number  of  decades.  One  of  the  most  im- 
portant of  these,  M.  W.  Drobisch,  projected  an  ambitious 
programme  for  psychology,  claiming  for  it  an  insight  into 
the  true  nature  of  reality  beyond  that  of  any  other  science.1 
In  the  contents  of  consciousness,  in  the  variety  of  our  idea- 
tional, affective,  and  desiderative  life,  we  observe  the  inner 
processes  themselves  which  constitute  spiritual  life.  The 
first  task  of  psychology  is  the  entire  exclusion  of  meta- 
physics and  the  creation  of  an  empirical  psychology  which 
should  be  really  worthy  of  the  name.  A related  prob- 
lem is  the  formulation  of  a mathematical  theory  of  mental 
life.  A third  problem  consists  in  the  application  of  the 
results  obtained  to  epistemological  and  metaphysical  ques- 
tions. It  is  in  the  first  of  these  attempts  that  the  influence 
of  natural  science,  for  which  the  exact  spirit  of  Herbartian 
psychology  has  such  a deep  affinity,  makes  itself  most  def- 
initely felt.  The  man  who  contributed  most  in  this  direc- 
tion was  Theodor  Waitz,2  who  abandoned  the  Herbartian 
scheme  and  regarded  psychology  as  one  of  the  natural 

1 Empirische  Psychologie  nach  naturmssenschaftlicher  Methode,  1842, 
2d  ed.,  1898,  Einl.,  pp.  9 ff. 

2 Lehrbuch  der  Psychologie  als  Naturwissenschaft,  1849. 


108 


HISTORY  OF  PSYCHOLOGY 


sciences.  The  Herbartian  tradition  was  maintained  more 
strictly  by  W.  F.  Volkmann,  who  made  a conspicuous 
attempt  to  prove  the  services  of  realism  in  the  realm  of 
psychology. 

An  intermediate  tendency  is  represented  by  Hermann 
Lotze,  the  most  independent  of  the  group  of  psychologists 
who  usher  in  the  most  recent  development  of  psychology. 
He  sought  to  formulate  a physiology  of  mind  but  maintained, 
at  the  same  time,  that  the  results  must  be  interpreted  in 
the  light  of  general  psychological  conceptions,  and  this  for 
the  reason  that  he  had  long  ago  ascertained  secretly,  by 
statistical  methods,  that  the  average  life  of  the  great  posi- 
tive discoveries  of  exact  physiology  had  been  four  years! 
It  is  true  that  Herbart  had  admitted  the  existence  of  phys- 
iological conditions  of  mental  states.  The  significance  of 
the  body  for  states  of  consciousness  is  proved  by  the  influ- 
ence upon  them  which  the  body  exerts,  by  the  bodily  res- 
onance observable  in  connection  with  certain  psychical 
states,  and  by  the  co-operation  of  the  body  in  the  produc- 
tion of  volitional  acts.  Lotze,  however,  was  the  first  to 
take  account  of  the  physiological  conditions  of  mental  life 
in  any  thoroughgoing  or  extensive  way.1  He  did  not  con- 
tent himself,  for  example,  with  simply  placing  sensation 
and  feeling  side  by  side,  as  two  elements  of  mental  life,  but 
analyzed  the  genesis  of  simple  sensation  itself  into  a series 
of  distinguishable  stages.  In  the  first  place,  the  external 
stimulus  is  transformed  into  the  excitation  of  the  sense- 
organ;  this,  in  turn,  produces  the  nervous  process  which  is 
eventually  to  result  in  sensation,  and,  finally,  we  have  the 
problematic  modifications  within  the  brain  itself.  Here 
the  process  emerges  from  the  physical , realm.  The  impres- 
sion which  the  excitations  within  the  nervous  system  pro- 

1 Cf.  with  this  the  historical  retrospect  by  Kiilpe,  Grundriss  der  Psy- 
chology, 1893,  p.  27.  [English  translation,  p.  26.  Trs.] 


EXPLANATORY  PSYCHOLOGY 


109 


duce  in  the  soul  might,  in  the  first  instance,  be  an  uncon- 
scious process,  which  is  then  succeeded,  as  a sixth  member 
of  our  series,  by  a simple  sensation.  As  a seventh  stage 
might  be  mentioned  attention,  which  conscious  sensations 
receive  in  greater  or  less  degree.  With  distinctions  such  as 
these,  derived  from  the  modern  physiology  of  the  senses, 
are  combined  ideas  reminiscent  of  the  Herbartian  mechanics 
of  ideas,  which  lead  to  a number  of  general  propositions 
concerning  the  relation  of  impressions  in  the  soul,  as  follows:1 
(1)  If  two  impressions  which  are  qualitatively  the  same  en- 
ter consciousness,  the  result  is  a simple  sensation  of  double 
the  strength  of  each  taken  separately.  (2)  If  two  impres- 
sions are  qualitatively  dissimilar,  but  are  at  the  same  time 
comparable,  it  depends  upon  the  mental  excitation  in  which 
they  are  produced  whether  they  fuse  or  not.  Two  colors, 
for  example,  if  not  separated  spatially,  must  fuse.  (3)  If  a 
number  of  different  nerve-fibres  receive  an  equal  amount 
of  the  same  stimulus,  and  if  the  impressions  really  sum  them- 
selves, the  intensity  of  the  resulting  sensation  will  be  propor- 
tional to  the  sum  of  the  nerve-fibres  through  which  it  is 
excited.  (4)  If  a stimulus  of  a constant  amount  is  dis- 
tributed among  a number  of  nerve-fibres,  the  resulting  sen- 
sation is  much  weaker  than  if  the  total  stimulus  is  carried 
by  a single  nerve-fibre.  (5)  Disparate  stimuli,  like  colors 
or  tones,  do  not  result  in  an  intermediate  sensation,  but 
only  in  a distribution  of  attention. 

It  is  remarkable  how  many  psychological  problems  are 
affected  by  the  foregoing  generalizations.  In  connection 
with  the  first  of  these  propositions,  renewed  attempts  have 
been  made  at  an  elementary  construction  of  sensation.  The 
second  suggests  presuppositions  which  were  to  serve  as  the 
starting-points  for  some  purely  psychological  theories  of 
space.  Taken  in  conjunction  with  the  fifth,  it  also  suggests 
1 Meiicinische  P$ych*l*§i»,  1|52,  99.  23#  ff. 


110 


HISTORY  OF  PSYCHOLOGY 


the  phenomena  of  mental  rivalry.  The  third  and  fourth 
propositions,  finally,  are  attempts  to  bring  into  relation  the 
intensity  of  sensation  and  the  retinal  distribution  of  the 
stimulus,  a question  which  was  later  taken  up  again  by 
Fechner. 

In  the  discussion  of  the  complex  functions  the  moral 
point  of  view  characteristic  of  Lotze’s  thought  occasionally 
comes  into  the  foreground.  He  applies  the  law  of  persis- 
tence, which  it  is  so  tempting  to  invoke  in  support  of  the 
retention  of  memory  images  in  the  brain,  to  the  soul  itself. 
The  difficulty  of  understanding  how  an  infinite  number  of 
impressions  can  persist  in  one  substance  is  no  greater  in  the 
case  of  the  soul  than  in  the  case  of  the  brain.  The  soul 
hypothesis,  however,  satisfies  our  moral  needs  more  ade- 
quately than  the  other.  Lotze  accordingly  proceeds  upon 
the  assumption  that  memory  as  well  as  miscellaneous  recog- 
nition and  the  course  of  ideas  are  conceivable  without  the 
co-operation  of  the  brain.1  Lotze’s  psychology  here  issues 
in  a pure  spiritualism,  in  which  the  rigor  of  psychological 
analysis  is  combined  with  a disposition  to  yield  to  moral 
interests  and  needs.2 

Among  those  who  have  helped  to  preserve  the  funda- 
mental idea  of  Herbart’s  psychical  mechanics  is  Lipps. 
Although  he  shows  a closer  affiliation  with  the  views  of  Her- 
bart  in  his  first  principal  work,  Grundtatsachen  des  Seelenle- 
bens  (1883),  than  in  his  subsequent  publications,  neverthe- 
less, the  aim  which  underlies  all  his  work  is  to  bring  the 
realm  of  psychical  processes  under  the  reign  of  necessary  law. 
If  one  were  asked  to  state  the  principal  difference  between 
the  psychology  of  Herbart  and  that  of  Lipps,  it  might  be 
said  to  consist  in  the  attempt  of  Lipps  to  substitute  for  the 
mechanism  of  conscious  psychic  processes,  such  as  Herbart 
contemplated,  the  mechanism  of  unconscious  psychic  proc- 
1 Op.  cit.,  p.  473.  2 Cf.  above,  p.  30. 


EXPLANATORY  PSYCHOLOGY 


111 


esses,  which  was  to  serve  as  the  conceptual  basis  for  the 
explanation  of  the  phenomena  of  consciousness. 

To  the  Herbartian  school  is  also  due  the  first  stimulus 
to  the  development  of  ethnic  psychology,  which  has  become 
one  of  the  most  important  branches  of  comparative  psy- 
chology. 


3.  Comparative  Psychology 


The  term  comparative  psychology  might  be  said  to  include 
those  branches  of  psychology  which  go  beyond  the  realm 
of  phenomena  given  in  individual  self-observation  and  which 
depend  in  the  main  upon  the  method  of  comparison.  Ethnic 
psychology  and,  in  large  part,  animal  psychology  come 
under  this  classification.  The  influence  of  Darwinism  which 
is  noticeable  in  the  treatment  of  a number  of  special  prob- 
lems is  felt  mainly  in  this  field.  As  a special  branch  of 
comparative  psychology  may  also  be  mentioned  individual  j 
psychology,  in  so  far  as  it  attempts  to  separate  individual  / 
from  general  psychical  phenomena  by  the  aid  of  compara-  / 
tive  methods. 


(a)  Ethnic  Psychology 

The  science  of  ethnic  psychology  is  usually  said  to  have\ 
been  founded  by  Steinthal  and  Lazarus,  who  issued  their 
Zeitschrift  fur  Volkerpsychologie  in  I860.  As  we  look  back 
to  those  early  beginnings  from  the  point  of  view  of  the  con- 
cepts of  ethnic  psychology  originated  in  recent  times  by 
Wundt,  the  psychical  mechanics  of  Herbart  seems  the  most 
inappropriate  point  of  departure  possible  for  the  considera- 
tion of  this  group  of  phenomena,  particularly  since  the  in- 
vestigators referred  to,  in  spite  of  the  wide  scope  of  their 
programme,  regarded  ethnic  psychology  merely  as  a field  for 


112 


HISTORY  OF  PSYCHOLOGY 


the  application  of  the  principles  of  psychical  mechanics. 
Nevertheless,  the  general  character  of  the  Herbartian  specu- 
lation was  not  without  aid  to  these  investigators.1  A thinker 
trained  in  the  abstractions  of  the  Herbartian  system,  which 
dealt  only  with  the  general  relations  obtaining  among  mu- 
tually inhibitive  intensive  magnitudes,  would  readily  substi- 
tute for  the  latter  corresponding  factors  when  these  mani- 
fested themselves  in  human  society. 

The  beginnings  of  ethnic  psychology  in  England  were  in- 
dependent of  these  efforts  and  were  dominated  by  different 
conceptions.  It  was  English  empirical  psychology  that  was 
the  first  to  enter  the  broad  field  of  ethnological  phenomena 
for  the  purpose  of  utilizing  these  phenomena  for  psycho- 
logical purposes.  The  investigations  of  prehistoric  man  and 
the  beginnings  of  civilization  by  Lubbock  and  Tylor  (1865) 
opened  the  way.  But  it  was  the  psychology  of  Herbert 
Spencer,  based  upon  the  evolutionary  idea,  which  was  bound 
to  transcend  the  standpoint  and  to  overstep  the  limits  of  a 
merely  individual  psychology.  In  spite,  however,  of  the 
wealth  of  ethnological  data  displayed  in  these  and  similar 
works,  they  tended  after  all  to  run  to  philosophy  of  history 
rather  than  to  remain  pure  ethnic  psychology. 

) These  modern  developments  were  anticipated  early  in  the 
eighteenth  century  by  G.  B.  Vico  (1668-1744), 2 who  simi- 
larly combined  problems  of  the  philosophy  of  history  with 
reflections  in  ethnic  psychology  for  his  interpretation  of  the 
historic  process  as  a process  conditioned  by  psychological 
laws.  It  is  true  that,  in  so  far  as  he  confined  himself  to  a 
comparison  of  the  life  of  peoples  separated  from  each  other 
in  space  and  time,  his  method  was  merely  a method  of  his- 
torical induction;  nevertheless,  the  subjects  investigated  by 

1 See  Wundt,  Volkerpsychologie,  I,  2d  ed.,  1904,  Einl.,  pp.  18  ff. 

2 In  his  work,  Sdenza  nuova  d’intorno  alia  commune  natura  delle  na- 
zioni  (1730). 


EXPLANATORY  PSYCHOLOGY 


113 


him — language,  myth,  custom,  and  laws — belong  without 
question  to  ethnic  psychology. 


( b ) Animal  Psychology 1 

The  contention  of  Descartes  that  animals  were  soulless 
automata,  a conception  popular  at  the  time,  was  not  seri- 
ously controverted  until  the  eighteenth  century.  Condillac 
ascribed  to  animals  a soul  life  essentially  resembling  that 
of  man.2  There  are,  according  to  him,  no  specific  differences 
between  man  and  the  animals  as  regards  mental  constitu- 
tion, the  difference  consisting  merely  in  the  greater  range  of 
man’s  experiences.  The  narrow  range  of  an  animal’s  experi- 
ence is  due  to  its  low  physical  development,  and  particularly 
to  the  comparatively  low  development  of  its  sense-organs. 
The  influence  of  sensualism,  which  tends  to  correlate  the 
range  of  experience  and  knowledge  with  the  development  of 
sense-organs,  is  clearly  evident  here.  Condillac’s  position 
was  controverted  by  H.  S.  Reimarus,3  one  of  the  early  cham- 
pions of  deism  in  Germany.  The  instincts  of  animals  are 
not  acquirements  due  to  intelligence  and  experience  but  are 
purely  congenital  traits.  As  the  bearer  of  ideals  and  possessor 
of  intelligence  and  free  will,  man,  compared  with  the  lower, 
animals,  is  simply  a higher  order  of  being.  In  his  analysis 
of  the  animal  mind  Reimarus  accordingly  confines  himself 
to  the  determination  of  these  congenital  instincts.  He  finds 
ten  classes  of  these,  and  the  adaptations  which  they  severally 
show  furnish  him  with  arguments  for  the  wisdom  of  the 
Creator. 

The  influence  of  the  semitheological  doctrines  of  Reima- 
rus upon  natural  scientists  was  practically  negligible.  His 


1 Cf.  with  the  following  E.  Rddl,  Geschichte  der  biologischen  Theorien, 
II,  1909,  pp.  427#.,  214#. 

2 Traite  des  animaux,  Amsterdam,  1755. 

3Allgemeine  Betracht.  u.  d.  Triebe  d.  Tiere,  1760. 


114 


HISTORY  OF  PSYCHOLOGY 


view  of  instinct,  however,  was  revived  in  the  nineteenth  cen- 
tury in  the  form  of  a certain  conception  growing  out  of  the 
German  philosophy  of  nature.  Starting  with  the  phenom- 
ena of  the  simplest  instinctive  activities,  Fichte  had  ar- 
rived at  the  notion  of  the  subject  as  pure  activity.  For 
Schelling  the  animal  instincts  were  the  significant  activities 
of  the  same  power  which  reveals  itself  most  profoundly  in 
art.  The  metaphysical  will  of  Schopenhauer,  too,  nowhere 
reveals  itself  more  immediately  than  in  instinct,  and  Hart- 
mann bases  his  conception  of  the  unconscious,  which  is  of 
such  central  importance  in  his  system,  largely  upon  the  doc- 
trine of  instinct.  One  of  the  best  evidences  of  the  reflex  in- 
fluence of  these  general  philosophical  ideas  upon  psychology 
are  the  writings  of  the  physician  C.  G.  Carus,1  which  seek 
to  portray,  often  by  the  aid  of  myth  and  allegory,  the  grad- 
ual growth  of  consciousness  in  the  animal  world.  Man  and 
the  lower  animals  are  bound  together  by  many  analogies. 
Observation  gives  place  to  admiration  of  the  hidden  essence 
which  comes  to  expression,  e.  g.,  in  the  profound  symbolism 
of  the  spiral  line  of  the  snail;  by  unbridled  analogies  the 
author  lifts  himself  into  the  realm  of  metaphysics  and  of 
those  spiritualistic  ideas  with  which  we  have  already  become 
acquainted.2 

Natural  science,  meanwhile,  in  its  more  exact  forms,  took 
its  starting-point  from  Condillac.  Lamarck  was  prominent 
among  those  who  developed  the  notion  of  evolution  which 
was  suggested  by  Condillac.  He  enriched  the  current  doc- 
trine by  the  important  addition  of  the  idea  that  the  results 
of  the  experiences  gained  during  the  life  of  the  individual 
do  not  disappear  at  the  death  of  the  individual  but  are  trans- 
mitted to  the  offspring  by  heredity.  The  views  of  the  psy- 

1 Psychologie  oder  Geschichte  der  Seele  in  der  Reihenfolge  der  Tierwelt, 
1866. 

2 See  above,  p.  30. 


EXPLANATORY  PSYCHOLOGY 


115 


chical  life  of  animals  held  by  Darwin  were  somewhat  naive, 
since  he  ascribed  to  animals  a soul  life  essentially  similar  to 
man’s  but  existing  in  a somewhat  masked  or  undeveloped 
form.  Instinct  is  to  be  explained  as  inherited  habit,  and 
the  differences  among  instincts  are  to  be  accounted  for 
by  reference  to  the  same  process  of  natural  selection  by 
which  we  explain  differences  of  bodily  structure.  Since 
Wundt’s  studies  in  animal  psychology,1  this  branch  has 
become  more  closely  affiliated  with  general  psychology.  A 
singular  revival  of  long-forgotten  ideas  which  carry  one  back 
to  Scholasticism  is  found  in  Erich  Wasmann.2  He  agrees 
with  Reimarus  in  separating  instinct  entirely  from  intelli- 
gence. Intelligent  actions  differ  from  instinctive  through 
the  presence  in  the  former  of  the  consciousness  of  end.  The 
absence  of  the  consciousness  of  end  and  of  the  power  of 
abstraction  in  the  lower  animals  constitute  an  impassable 
gulf,  according  to  Wasmann,  between  man  and  these  lower 
forms.  An  effective  counter-influence  to  such  views  is 
found  in  modern  experimental  animal  psychology,  which 
even  goes  to  the  opposite  extreme,  as  in  Loeb’s  theories  of 
the  chemical  reactions  of  lower  animals.3 


(c)  Influence  of  Darwinism 

The  influence  of  Darwin  upon  psychology  was  also  evi- 
dent in  connection  with  many  special  problems.  Thus  we 
meet  with  the  attempt  to  explain  color  sensations  from  an 
evolutionary  point  of  view.  After  the  English  statesman 
W.  E.  Gladstone  and  L.  Geiger  had  contended  that  the 
Greeks— Homer,  for  example — had  not  been  able  to  distin- 

1 Vorlesungen  uber  die  Menschen-  und  Tierseele,  1863,  5th  ed.,  1911. 
[Engl.  tr.  ( Human  and  Animal  Psychology)  by  Creighton  and  Titchener, 
New  York,  1895.  Trs.] 

2 Instinct  und  Intelligenz  im  Tierreich,  1899. 

5 See  above,  p.  42. 


HISTORY  OF  PSYCHOLOGY 


guish  blue  from  black  or  gray  from  green,  H.  Magnus1 
sought  to  show  that  man  was  originally  entirely  color- 
blind. The  order  of  colors  in  the  spectrum  from  red  to  violet 
is  claimed  to  be  the  order  in  which  human  sensitivity  to 
the  various  color-tones  developed;  and  Magnus  does  not 
shrink  from  the  conclusion  that  sensitivity  to  ultra-violet 
light  will  at  some  future  time  be  developed. 

Similarly,  new  points  of  view  were  developed  in  the  study 
of  the  origin  of  language.  Darwin’s  own  views  stood  mid- 
way between  the  theory  of  imitation  and  that  of  instinctive 
sounds,  the  two  theories  which  formed  the  most  natural 
approach  to  a psychological  comprehension  of  the  problem 
of  language.  He  held  that  language  originated  partly  in 
the  imitation  of  natural  sounds,  partly  in  the  instinctive 
cries  of  man  himself.  Starting  from  a similar  point  of  view, 
G.  Jager  sought  to  explain  the  development  of  human  lan- 
guage from  the  sounds  uttered  by  animals.2  He  describes 
in  detail  the  stages  which  occurred,  as  he  supposed,  in  the 
development  of  expression  among  animals,  from  accidental 
to  voluntary  utterance,  from  mere  motor  discharge  to  com- 
munication. The  influence  of  bodily  structure,  too,  is  taken 
into  account.  Thus  quadrupeds,  for  example,  whose  chest 
movements  are  affected  by  their  mode  of  locomotion,  lack 
the  delicacy  in  the  control  of  respiratory  movements  which 
is  requisite  for  speaking  or  singing.  These  biological  fan- 
cies, however,  were  soon  abandoned  again,  along  with  vari- 
ous other  speculations,  such  as  the  genealogical  theories  of 
language  of  Schleicher,  the  theory  that  inarticulate  inter- 
jection formed  the  substrate  out  of  which  articulate  lan- 
guage developed,  and  the  like. 

Evolutionary  psychology  also  made  a number  of  attempts, 
which  owe  their  origin  to  modern  biology,  to  determine  the 

1 Die  geschichtliche  Entwicklung  des  Farbensinnes,  1877. 

2 Uber  den  Ursprung  der  menschlichen  Sprache,  1867  and  1869. 


EXPLANATORY  PSYCHOLOGY 


117 


elementary  psychical  attribute  of  organized  matter.  We 
have  to  do  here  with  the  transformation  of  the  problem  of 
determining  the  psychical  element  which  is  co-ordinate  with 
the  element  of  matter,  a problem  originating  in  metaphys- 
ical psychology,  or  in  the  border  field  of  empirical  psy- 
chology, into  the  problem  of  the  kind  of  psychical  activity 
which  characterizes  various  stages  of  organic  evolution. 
Hering  named  memory  as  the  elementary  psychic  character- 
istic of  organized  matter.1  Racial  memory  is  developed  in 
the  evolutionary  series  as  a whole,  by  heredity.  The  related 
distinction  between  individual  and  phyletic  memory  subse- 
quently found  its  way  into  many  psychogenetic  considera- 
tions, such  as  those  of  W.  Preyer.2 

(d)  Individual  Psychology 

A last  branch  of  comparative  psychology  occupies  itself 
with  individual  differences.  If  we  pass  over  the  secular 
psychology  of  the  Renaissance,3  the  main  ideas  of  individual 
psychology  are  found  in  that  versatile  era,  the  period  of  the 
Enlightenment.  Herder,  in  1778,  voiced  the  demand  for  a 
“characteristic”  psychology.  Oddly,  he  directed  his  polemic 
against  the  ars  charaderistica  which  had  originated  in  the 
philosophy  of  Leibniz  and  which  Ploucquet  and  Lambert 
sought  to  develop  into  a general  science  of  conceptual  signs. 
Psychology,  he  urged,  should  take  particular  care  not  to  lose 
itself  in  such  fruitless  generalities.  Herder  recommends  as 
a model  for  psychologists  the  physiology  of  Haller,  whose 
law  of  muscular  sensitivity  Herder  proclaimed  as  the  fun- 
damental law  of  sensation.  Spirit-filled,  like  Pygmalion’s 
statue,  Haller’s  physiological  treatise  is  to  be  raised  to  the 
rank  of  psychology.  A year  later  appeared  Feder’s  inves-  I 

1 Uber  das  Geddchtnis  als  Funktion  der  organischen  Materie,  1870. 

2 Die  Seele  des  Kindes,  p.  230.  3 Cf.  p.  57,  above. 


118 


HISTORY  OF  PSYCHOLOGY 


tigations  of  the  will,  in  which  the  idea  of  special  psychol- 
ogy was  also  definitely  expressed.  These  various  movements 
and  ideas  were  voiced  in  the  Magazin  filr  Erfahrungsseelen- 
lehre,  published  by  C.  P.  Moritz,  founded  in  1782.  The 
whole  problem  of  individual  psychology,  the  psychology  of 
individual  differences,  has  come  into  special  prominence  in 
recent  years  in  its  connection  with  the  applications  of  psy- 
chology, particularly  to  the  field  of  education.  An  initial 
problem  here,  according  to  L.  W.  Stern,  is  created  by  the 
fact  that  psychology,  as  an  analytic  science,  which  isolates 
mental  processes,  stands  in  fundamental  contradiction  to  all 
those  branches  for  which  the  mental  life,  as  an  individual 
whole,  i.  e.,  as  a personality,  is  of  significance.1  The  fact 
that  the  divisions  of  general  and  individual  psychology,  on 
the  one  hand,  and  of  pure  and  applied  psychology,  on  the 
other,  cross  each  other,  leads  to  one  of  the  most  actively 
controverted  questions  of  contemporary  psychology. 

The  various  tendencies  of  comparative  psychology  which 
devote  themselves  to  the  study  of  special  social  groups 
cannot  be  followed  in  detail  here.  They  belong,  in  any 
event,  mainly  to  the  present.  Occasionally  we  find  striking 
discrepancies  between  investigations  of  this  sort,  which  are 
not  always  undertaken  with  purely  psychological  motives, 
and  exact  psychological  reflection.  Here  belong  hypotheses 
like  those  of  Weininger  which  have  achieved  an  ephemeral 
reputation,  and  according  to  which  the  specific  difference 
between  the  sexes  is  to  be  explained  by  reference  to  the 
wholly  untenable  conception  of  a mental  state  in  which  sen- 
sation and  feeling  have  not  yet  become  differentiated  from 
each  other.2 

1 Psychologie  der  Aussage,  Heft  I,  1903,  p.  15. 

8 Weininger,  Geschlecht  und  Character,  7th  ed.,  1905,  pp.  127  /. 


EXPLANATORY  PSYCHOLOGY 


119 


4ft 

4.  Influences  of  Natural  Science 

The  last  stage  in  the  development  of  modern  psychology 
is  characterized  by  the  influence  upon  it  of  natural  science. 
The  effect  of  this  influence  was  not  that  the  tendencies 
of  explanatory  psychology  which  were  motived  by  purely 
psychological  considerations,  an  account  of  which  we  have 
already  given,  were  supplanted  by  the  modes  of  thought 
characteristic  of  natural  science.  Rather  did  the  attentive 
consideration  of  the  methods  of  science  and  of  the  border 
problems  of  psychology  and  science  bring  the  unique  char- 
acter of  the  problems  of  psychology  into  clearer  relief. 

The  contact  of  psychology  with  natural  science  was  thus 
manifold.  That  the  idea  of  the  regularity  of  events,  which 
had  lent  vitality  to  science  since  the  Renaissance,  also  served 
as  an  ideal  in  psychology  can  be  proved  by  the  evidence  of 
centuries.1  It  was  in  the  nineteenth  century,  however,  that 
the  growing  knowledge  of  the  central  nervous  system  came 
to  the  aid  of  the  older  efforts  to  determine  the  physiological 
basis  for  a definitely  outlined  system  of  psychological  ideas, 
thus  resulting  in  the  so-called  modern  science  of  phrenology. 
But  the  method  of  science,  too,  found  its  way  into  psy- 
chology. It  came  from  the  direction  where  the  problems  of 
science  and  of  psychology  find  a common  meeting  ground, 
that  of  the  physiology  of  the  senses.  Here  the  basis  was  ; 
laid  upon  which  experimental  psychology  as  an  independent 
branch  of  investigation  could  be  founded. 


(a)  The  Newer  Phrenology 

Phrenology  has  a long  preliminary  history  in  the  various 
theories  regarding  the  seat  of  the  soul.  Only  the  roles,  so  to 
1 Cf.  Chapter  VIII,  1,  below. 


HISTORY  OF  PSYCHOLOGY 


120 


/-speak,  in  these  two  branches,  were  in  a way  interchanged. 
/ In  the  older  theories  the  point  of  departure  was  psychology, 
/ which  accordingly  reacted  upon  brain  physiology;  and  the 
l comparatively  meagre  knowledge  of  brain  anatomy  gave 
\ unrestricted  play  to  the  most  extravagant  hypotheses.  The 
psychological  motive  which  led  Descartes  to  locate  the  soul 
in  the  pineal  gland,  strange  as  it  appears  to  us  nowadays, 
dominated  psychology  for  centuries.  Since  we  can  have  only 
a single  impression  of  an  object  at  any  one  time,  there  must 
be  some  place  where  the  separate  views  from  the  two  eyes, 
for  example,  or  any  other  such  disparate  impressions,  are 
united  into  a single  whole  before  they  enter  the  soul.1  The 
organ  in  which  this  fusion  takes  place  must,  it  is  evident, 
be  one  which  is  not  duplicated  in  the  brain.  The  motive, 
however,  which  prompted  Descartes  to  decide  upon  the  pin- 
eal gland  was  that  it  was  only  here  that  the  unification 
of  impressions  could  be  accomplished  by  means  of  the  ani- 
mal spirits  ( spiritus  animates ) which  fill  the  ventricular  cavi- 
ties of  the  brain.  The  fundamental  idea  of  Descartes  that 
the  coalescence  of  disparate  mental  impressions  could  occur 
only  through  their  conjunction  in  some  one  point  of  the 
brain  appealed  so  strongly  to  the  psychologists  of  the  seven- 
teenth and  eighteenth  centuries  that  there  was  hardly  an 
unpaired  structure  in  the  brain  which  was  not  at  some 
time  or  other  a candidate  for  the  honor  of  being  the  seat 
of  the  soul.  Lancisi  and  Bonnet  held  the  seat  of  the  soul 
to  be  the  corpus  callosum,  Digby  the  septum  pellucidum, 
Haller  the  pons  Varolii;  Boerhave  located  it  in  the  medulla 
oblongata,  Plattner  in  the  corpora  quadrigemina. 

/The  doctrine  of  the  seat  of  the  soul  combined  with  the 
faculty  psychology  which,  in  comparison  with  the  Cartesian 
doctrine  of  the  soul  as  a simple,  indivisible  substance,  already 
represented  considerable  analysis,  to  form  the  well-known 
1 Les  passions  de  I’dme,  I,  p.  32. 


EXPLANATORY  PSYCHOLOGY 


121 


system  of  phrenology  of  F.  J.  Gall,1  a system  which  illustrates 
what  varied  psychological  tendencies  meet  in  the  psychology 
of  the  latter  part  of  the  eighteenth  century.  Gall  trans- 
formed the  fundamental  concepts  of  faculty  psychology  into 
organs  of  mind.  The  origin  and  connection  of  mental 
processes  were  ascribed  to  nerve  vibrations,  to  which  corre- 
sponded, on  the  psychological  side,  the  association  of  ideas. 
In  addition  to  various  fundamental  psychical  dispositions 
or  faculties  the  soul  has  a number  of  characteristics,  such 
as  intelligence,  will,  attention,  and  the  like.  Each  faculty 
possesses  all  these  attributes.  The  number  of  these  funda- 
mental traits  is  said  to  correspond  to  the  number  of  instincts, 
of  which  Gall  enumerated  twenty-seven,  such  as  sex,  philo- 
progenitiveness, friendship,  cunning,  pride,  avarice,  and  the 
like.  Assuming  that  each  of  these  faculties  was  matched  by 
a corresponding  brain  structure,  Gall  proceeded  to  elaborate 
the  practical  science  of  phrenology.  Since  the  brain  struc- 
tures in  question  are  located  superficially,  the  skull  would 
show  corresponding  conformations  which  can  be  easily  as- 
certained by  tactual  exploration,  thus  affording  an  objec- 
tive means  for  the  ascertainment  of  mental  endowment. 
Although  Gall  anticipated  many  modern  conceptions,  such 
as  those  of  congenital  tendencies  to  criminality  or  the  ten- 
dency of  supernormal  persons  to  insanity,  his  art  was  com- 
mercialized and  degenerated  into  charlatanism. 

The  untenability  of  Gall’s  phrenology  was  proved  in  the 
first  part  of  the  nineteenth  century  by  the  French  experi- 
mental psychologists  Magendie  and  Flourens.  Flourens 
ascribed  different  function-complexes  to  the  medulla  oblon- 
gata, the  corpora  quadrigemina,  and  to  the  cerebellum  and 
cerebrum.  The  last  vestige  of  the  old  question  of  the  seat 
of  the  soul  is  found  in  his  influential  doctrine  of  the  vital 

1 Gall,  Vorlesungen  uber  die  Verrichtungen  des  Gehirns.  Herausge- 
geben  von  H.  G.  C.  von  Selpert,  1805. 


122 


HISTORY  OF  PSYCHOLOGY 


nodes.  The  point  of  the  V-formed  gray  mass  at  the  beak  of 
the  so-called  calamus  scriptorius,  with  which  the  fourth  ven- 
tricle passes  over  into  the  fissure  of  the  spinal  chord,  is  the 
seat  of  life  in  the  sense  that  its  extirpation  or  injury  results 
in  instant  death.1  The  psychical  functions  proper,  how- 
ever, remain  localized  in  the  entire  area  of  the  cerebral  hem- 
ispheres. The  functions  in  question  are  intelligence  and  will, 
whose  localization  he  conceived  of  in  such  wise  that  the 
most  minute  part  of  the  organs  involved  could  act  in  place 
of  the  whole.  Intelligence  and  will,  however,  are  very  com- 
plex functions,  and  it  is  difficult  to  see  how  they  can  be 
localized  in  the  smallest  structure  of  an  organ  so  highly 
differentiated  as  the  brain.  The  disposition  to  take  refuge 
in  the  older-style  phrenology  in  order  to  escape  from  these 
difficulties  was  encouraged  by  the  partial  confirmation  of 
the  theory  of  Gall  through  the  discovery  by  Broca,  in  1861, 
of  the  so-called  centre  of  speech.  The  advance  of  modern 
phrenology,  as  distinguished  from  the  particular  system  of 
Gall,  consisted,  in  the  first  place,  in  the  substitution  for  the 
older  organs  of  mind  certain  special  centres  or  areas  con- 
nected with  certain  peripheral  functions  such  as  the  move- 
ments of  co-ordinated  muscle  groups.  In  the  second  place, 
the  inner  senses  of  Gall  were  forced  to  give  place  to  psychi- 
cal elements,  usually  sensations  and  ideas,  which  the  psy- 
chology of  Herbart  had  brought  into  prominence.  It  was  ac- 
cordingly assumed  that  the  cortex  contained  sensory  centres 
for  the  reception  of  incoming  stimuli  and  for  the  initiation 
of  motor  innervations.  Each  of  these  centres,  in  turn,  con- 
tains sensory  and  idea  cells.  The  latter  possess  the  power 
of  reviving  sensations,  as  the  excitement  of  the  sensory 
cells  tends  to  communicate  itself  to  the  idea  cells.  This 
was  the  form  of  the  theory  as  taught  by  Meynert  and  as 
later  applied  especially  by  H.  Munk,  who  gave  it  consider- 
able currency  among  brain  physiologists. 

1 Rech.  exper.  sur  lesfond.  du  syst.  nerv.,  2d  ed.,  1842,  p.  204. 


EXPLANATORY  PSYCHOLOGY 


123 


Closer  to  the  results  of  psychological  analysis  is  a second 
form  of  phrenology  which  separates  the  areas  in  which  the 
connections  among  sensations,  and  probably  also  their  repro- 
duction and  the  complex  psychical  processes,  occur  from 
the  ideational  centres,  as  special  association  centres.  Thus 
the  psychological  services  of  the  association  theory  find 
recognition  in  the  field  of  pure  psychology. 

The  controversy  regarding  the  association  centres  psy- 
chology might  well  have  left  to  the  brain  physiologists. 
Aside  from  the  details  mentioned,  two  results  were  reached 
which  were  of  general  interest  for  psychology.  In  the  first 
place,  the  question  regarding  the  seat  of  the  soul,  which  had 
occupied  psychology  for  centuries,  was  definitely  rendered 
meaningless  by  the  discovery  of  the  motor  areas  by  Fritsch 
and  Hitzig.  In  the  second  place,  the  results  of  the  study 
of  brain  physiology  confirmed  anew  the  inconceivable  com- 
plexity of  the  apparently  most  simple  mental  processes. 
How  many  components  might  be  contained  in  a given  men- 
tal process  of  which  no  trace  appears  in  consciousness  was 
revealed  especially  by  the  study  of  those  cases  of  brain 
lesion  which  resulted  in  the  splitting  up  of  mental  factors 
which  ordinarily  occur  together  and  the  disappearance  of 
a given  factor  from  the  original  complex.1 

( b ) The  Influence  of  Sense  Physiology  \ 

In  spite  of  the  close  relationship  which  existed  between  \ 
sense  physiology  and  psychology,  owing  to  their  common  ' 
connection  with  the  problem  of  perception,  the  results  of 
this  relation  were  for  a long  time  sufficiently  meagre.  The 
classical  physiologists  of  the  first  half  of  the  nineteenth  cen- 
tury were  themselves  obliged  to  make  acquaintance  with 

the  psychological  aspect  of  the  sensory  functions,  and  for  / 

/ 

1 Cf.  with  this  Wundt,  Grundzuge  der  -physiol ogischen  Psychologie,  I,/ 
6th  ed.,  pp.  341  ff. 


124 


HISTORY  OF  PSYCHOLOGY 


this  they  drew  freely  upon  the  philosophy  of  their  time. 
While  psychology  generally  followed  philosophical  specula- 
tion only  too  readily,  it  is  a remarkable  fact  that  the  tran- 
scendental idealism  of  Kant  influenced  psychology  only  in- 
directly, through  sense  physiology.  Johann  Muller,  who  is 
one  of  the  founders  of  the  newer  sense  physiology,  at  the 
early  age  of  twenty  defended  the  thesis,  Nemo  psychologus 
nisi  physiologus,  a principle  to  which  he  remained  loyal 
throughout  his  life.1  Rejecting  Schelling’s  philosophy  of 
nature,  he  returned  to  the  great  philosophers  of  the  past, 
Kant,  Spinoza,  and,  among  the  younger  thinkers,  particularly 
to  Herbart.  It  was  especially  the  Kantian  doctrine  of  space 
and  time  as  pure  intuitions  which  he  incorporated  into  his 
theory  of  perception.  In  seeking  for  a physiological  sub- 
strate of  these  transcendental  functions  he  found  the 
manifestations  of  this  directly  in  sensation.  The  retina,  for 
example,  feels  itself  as  spatially  extended.  Not  less  char- 
acteristic of  Muller’s  psychology  is  the  principle  of  the 
specific  energy  of  the  senses,  which  likewise  points  to  cer- 
tain philosophical  presuppositions  such  as  are  implied  in 
the  recognition  of  the  fact  that  psychical  processes,  and 
sensory  processes  in  particular,  are  incommensurable  with 
the  processes  of  the  external  world.  The  conception  of  the 
immediate  reality  and  of  the  incomparable  uniqueness  of 
psychical  processes  may  be  said  to  be  a common  conviction 
of  the  epoch  in  question.  In  this,  too,  perhaps,  consists  the 
greater  historical  significance  of  Muller  when  compared  with, 
say,  Purkinje,  who  also  ranks  as  one  of  the  founders  of 
modern  physiology.2  Few  of  his  observations,  which  extend 
to  nearly  all  branches  of  biology,  bear  his  name.  In  psy- 
chology the  greater  clearness  of  light  rays  of  short-wave 

1 Cf.  Stumpf,  “H.  v.  Helmholtz  u.  d.  neuere  Psychologie,”  Archiv  f. 
Gesch.  d.  Phil,  VIII,  1895,  pp.  303  ff. 

2 Purkinje,  Beobachtungen  und  Versuche  zur  Physiologie  der  Sinne,  2d 
ed.,  1825. 


EXPLANATORY  PSYCHOLOGY 


125 


length  in  dim  light  is  called  the  Purkinje  phenomenon,  and 
even  this  phenomenon  had  been  known  a long  time,  although 
it  had  not  been  utilized  for  the  theory  of  vision.  There  are 
numerous  precepts  in  the  Koran,  for  example,  which  are  to 
be  carried  out  at  a certain  hour  of  the  day,  owing  to  the 
fact  that  red  and  blue  threads  become  invisible  in  the 
twilight. 

It  was  Muller’s  school  which  was  to  give  to  the  world  the 
investigator  who  closed  once  and  for  all  the  gap  between 
physiology  and  psychology,  Helmholtz,  who  devoted  the 
main  strength  of  his  best  working  years  to  investigations  in 
physiological  and  experimental  psychology.  The  two  works 
upon  which  his  fame  mainly  rests,  his  Handbuch  der  pliy- 
siologischen  Optik  (1856-66)  and  his  Zur  Lehre  von  den 
Tonempfindungen  (1862),  were  devoted  to  the  psychology 
of  the  senses.  A mathematical  physicist  by  natural  endow- 
ment, his  principal  achievements  in  the  theory  of  vision 
and  audition  are  due  to  his  supreme  mastery  of  the  math- 
ematical technique  necessary  for  such  investigations.  Helm- 
holtz’s psychological  theories,  however,  have  a definite 
philosophical  background,  which  may  be  said  to  be  a more 
profound  version  of  the  idealism  of  Muller,  particularly  on 
the  epistemological  side.  Already  in  his  Konigsberg  inau- 
gural address,  Tiber  die  Natur  der  menschlichen  Sinnesem- 
pfindungen  (1852),  he  expounded  the  view  that  sense  ex- 
perience is  merely  a sign  of  the  existence  of  some  ob- 
jective quality,  never  a copy  which  in  some  way  reproduces 
its  real  nature.  Sensation  as  merely  a symbol  of  the  external 
world— this  doctrine  remained  fundamental  to  his  main  work 
and  served  as  an  explanation  of  the  structure  of  the  organs 
of  vision.  Dining  the  fifties  and  sixties  of  the  last  century7 
investigation  in  the  field  of  vision  was,  indeed,  extremely 
active,  as  the  names  of  Briicke,  Listing,  Volkmann,  Fech- 
ner,  Donders,  Panum,  and  others  will  recall,  and  this  serves 


126 


HISTORY  OF  PSYCHOLOGY 


to  explain,  to  some  extent,  how  such  a work  as  Helmholtz’s 
Physiological  Optics  could  come  into  existence.  Still,  the 
study  of  it  serves  only  to  increase  our  admiration  for  the 
creative  energy  of  its  author.  The  thoroughgoing  appli- 
cation of  the  experimental  method,  the  criteria  which  under- 
lie the  analysis  of  the  complex  sense-perceptions,  the  points 
of  view  for  the  derivation  of  the  psychical  products  from 
their  elements — these  achievements  have  never  been  lost 
to  psychology. 

f With  the  recognition  of  the  psychical  activities  involved 
in  perceptions  a large  group  of  psychological  problems 
admitting  of  exact  treatment  came  into  view,  with  the  re- 
sult that  sense  psychology  became  in  a very  genuine  sense 
a model  for  modern  experimental  psychology.  These  psy- 
chical activities  were  thought  by  Helmholtz  himself  to  be 
intellectual  activities,  an  elaboration,  logical  in  its  begin- 
nings and  gradually  becoming  unconscious,  of  sensation  ele- 
ments into  the  constituent  parts  of  perceptions.  This  empir- 
ical point  of  view,  which  stood  in  sharp  opposition  to  the 
nativism  in  sense  psychology  that  had  grown  out  of  Muller’s 
theories,  was  developed  in  close  dependence  upon  a philo- 
sophical writer  whose  Logic  was  one  of  the  most  influential 
works  of  the  middle  of  the  nineteenth  century,  John  Stuart 
Mill.  Mill’s  empirical  logic,  which  was  championed  in  Ger- 
many by  no  less  an  investigator  than  Justus  Liebig,  met 
with  a friendly  reception  particularly  among  natural  scien- 
tists. It  was  not  the  doctrine  of  association,  however,  which 
Helmholtz  borrowed  from  Mill  but  rather  the  doctrine,  so 
much  controverted,  of  unconscious  inductive  and  analogical 
inference,  an  idea  which  he  utilized  for  his  own  theories  of 
perception.  That  a natural  scientist  should  go  to  a logician 
for  light  on  psychological  questions  bears  witness  to  a truly 
remarkable  dislocation  of  the  boundary-lines  of  the  sciences. 

Although  Helmholtz  was  extremely  critical  of  philosophies 


EXPLANATORY  PSYCHOLOGY 


127 


of  nature,  declaring  his  own  allegiance  to  Mill’s  inductive 
method,  he  himself  now  and  then  unwittingly  fell  into  the 
mode  of  thinking  which  he  disparaged.  The  notion  of  de- 
velopment or  evolution  he  never  adopted.  His  analysis  of 
the  human  sensory  functions,  which,  in  spite  of  its  empirical 
character,  makes  no  use  of  the  evolutionary  principle,  oc- 
casionally reminds  one  of  the  attempts  of  the  philosophies 
of  nature  to  discover  the  laws  of  nature  in  the  activity 
of  human  intelligence.  The  sense  physiology  of  Helmholtz 
was,  of  course,  intended  to  be  predominantly  psychology. 
But  this  psychology  did  not  undertake  an  investigation  of 
the  simple  psychical  processes  but  assumed  certain  supposed 
psychical  processes  in  the  complex  activities  of  perception. 
The  eye  is  for  Helmholtz  a physical  apparatus  whose  func- 
tion it  is  to  mediate  certain  sensation  elements,  like  color, 
brightness,  and  so  forth.  Back  of  these  sensations,  how- 
ever, stands  intelligence,  which  acts  upon  them  like  a 
mental  faculty.  These  conceptions  are  connected  with  the 
attempt,  often  noticeable  in  Helmholtz,  to  dispose  of  cer- 
tain psychological  problems  involved  in  perception,  prob- 
lems which  are  not  amenable  to  treatment  of  the  degree  of 
exactitude  required  by  natural  science,  in  the  easiest  and 
quickest  way  possible.  In  this  way  Helmholtz  sometimes 
approached  perilously  near  to  a popular  intellectualism  of 
which  psychology  subsequently  had  to  free  itself. 


(c)  Experimental  Psychology 


The  problems  which  we  associate  with  experimental  psy- 
chology to-day  were  not  clearly  defined  until  very  recent 
times.  Most  of  the  beginnings  in  the  transformation  of  the 
method  of  psychology  were  made  by  the  psychology  of  the 
special  senses  which  has  just  been  described.  The  great 
physiologist  Ernst  Heinrich  Weber  took  the  idea,  which 


128 


HISTORY  OF  PSYCHOLOGY 


had,  indeed,  been  expressed  before,  namely,  that  one  must 
test  the  instruments  of  sensation  just  as  the  physicist  and 
chemist  must  test  the  instruments  with  which  they  work, 
and  made  it  the  starting-point  for  purely  psychological  in- 
vestigations. He  not  only  applied  this  test  in  his  own  investi- 
gations of  the  perceptions  of  space  and  of  pressure,  but  he 
also  pointed  out  the  psychological  conditions  of  reliability  in 
comparison,  as,  for  example,  of  the  differences  in  accuracy 
in  the  reception  of  simultaneous  and  successive  stimuli.  By 
varying  the  interval  between  the  two  stimuli  and  noting 
the  rate  of  diminishing  accuracy  with  the  increase  of  the 
interval  he  even  prepared  the  way  for  the  investigations  of 
memory  by  the  use  of  exact  methods.  “Since  the  oppor- 
tunity for  exact  measurements  of  mental  processes  comes  so 
rarely,”  he  wrote,  “I  recommend  these  investigations  to  the 
attention  of  psychologists.”  1 In  these  noteworthy  words 
we  meet  with  a distinct  recognition  of  the  importance  of 
exact  experimental  investigations.  The  law  which  has  been 
for  all  times  associated  with  the  name  of  Weber  was  in  the 
first  instance  merely  a result  of  observation.  In  his  inter- 
pretation of  this  fact  he  recognizes  a peculiarity  of  the 
comparison  of  sensations  in  the  fact  that  here  two  magni- 
tudes are  not  compared  with  a common  standard  of  mea- 
sure but  directly.2 

Psychology  did  not  at  once  heed  the  admirable  suggestions 
of  Weber.  Attempts  like  that  of  Bonatelli3  remained  iso- 
lated until  the  new  ideas  were  again  vitalized  by  philosophy. 
In  studying  the  history  of  psychology  one  is  frequently 
surprised  at  the  metaphysical  framework  which  supports 
psychological  systems.  Nevertheless,  it  must  not  be  forgot- 
ten that  many  psychological  points  of  view  owe  their  origin 

1 Tastsinn  und  Gemeingefuhl,  1846,  p.  546. 

2 Op.  cit.,  pp.  560/.;  cf.  Chapter  IX,  1 (6),  below. 

3 Dell’  Esperimento  in  Psicologia,  Brescia,  1858. 


EXPLANATORY  PSYCHOLOGY 


129 


to  their  relation  to  purely  philosophical  problems.  An 
illustration  of  this  is  Gustav  Theodor  Fechner,  who  com- 
bined the  exact  investigation  of  his  time  in  the  psychology 
of  the  senses  with  profound  and  fantastic  ideas  derived  from 
Schelling’s  philosophy  of  nature.  Starting  with  the  prob- 
lems of  the  philosophy  of  nature  of  Romanticism,  which  had 
been  obscured  by  the  dominant  philosophical  tradition  and 
which  was  kept  alive  by  a few  philosophical  scientists, 
Fechner  defined  psychophysics  as  the  exact  science  of  the 
relations  of  body  and  mind.  The  idea  that  body  and  mind 
represent  the  dual  manifestations  of  a fundamentally  unitary 
substance  already  formed  the  basis  of  his  Zendavesta,  pub- 
lished in  1851.  His  problem  was  to  ascertain  the  functional 
relation  between  the  two  series  of  phenomena  and,  in  par- 
ticular, to  establish  the  law  according  to  which  the  inten- 
sity of  mental  activity  varies  with  the  variation  in  the 
intensity  of  its  underlying  physical  activity.  Later  he 
expounded  schematically  certain  fundamental  relations  be- 
tween body  and  mind  and  between  lower  and  higher  forms 
of  spiritual  life  by  aid  of  the  relation  between  arithmetical 
series  of  lower  and  higher  orders.1  The  scheme  of  geo- 
metrical orders  led  him,  by  a somewhat  uncertain  line  of 
thought,  to  make  the  relative  increase  of  physical  vital 
energy  the  measure  of  the  increase  of  the  corresponding 
psychical  energy.2  With  this  was  connected  the  idea  that 
the  soul  would  sum  these  increments,  dy,  just  as  the  kinetic 
energy  of  a body  is  regarded  as  the  sum  of  its  absolute  in- 

d/3 

crements,  d/8.  Thus  the  fundamental  formula,  d^—K-^-,  and 

as  its  integral  the  formula  of  measurement  was  arrived  at. 
Without  any  thought  of  the  relation  of  this  formula  to 
Weber’s  law,  he  submitted  a paper  on  the  subject  to  W. 
Weber  in  1850,  who  was  impressed  with  the  correctness  and 

1 Zendavesta,  II,  p.  334.  2 Cf.  Psychophysik,  1860,  II,  p.  554. 


130 


HISTORY  OF  PSYCHOLOGY 


keenness  of  the  fundamental  idea,  although  unfortunately  it 
did  not  agree,  as  he  thought,  with  the  newer  discoveries. 
Fechner  at  length  discovered  an  empirical  foundation  in  the 
fundamental  psychophysical  law  for  brightnesses,  and  it 
was  not  until  after  a number  of  experiments  with  weights 
that  he  discovered  the  broad  basis  of  empirical  facts  in  the 
investigations  of  E.  H.  Weber. 

The  science  of  psychophysics,  as  Fechner  conceived  it,  is 
to  be  distinguished  from  psychology  proper  as  well  as  from 
physics,  and  aims  at  the  exact  determination  of  the  relation- 
ship between  psychical  and  physical  processes.  It  begins 
with  the  psychophysics  of  extra-organic  stimuli,  which  seeks 
to  determine  the  relation  between  consciousness  and  the 
external  world  and  which  serves  as  an  introduction  to  the 
psychophysics  of  the  bodily  organism.  For  there  is  a psy- 
chophysical activity  within  the  bodily  organism  which  stands 
intermediate  between  external  stimulus  and  sensation,  and 
it  is  the  relation  of  this  to  the  purely  psychical  activity 
within  that  the  “inner  psychophysics”  seeks  to  determine. 
To  this  field  are  transferred  Weber’s  law  and  the  phenome- 
non of  the  threshold,  under  the  assumption  that  psychophys- 
ical activity  is  proportional  to  the  stimulus.  In  the  further 
development  of  these  ideas  the  question  of  the  psychophys- 
ical continuity  and  discontinuity  comes  distinctly  into  the 
foreground.  The  latter  arises  when  the  movements  of  psy- 
chophysical activity  occur  below  a certain  limit  called  the 
conscious  threshold.  The  result  is  a number  of  psycho- 
physical steps  or  stages.  As  conscious  processes  which  are 
distinguishable  by  us  are  continuous  below  our  principal 
threshold,  so  also  our  own  consciousness  is  a part  of  a more 
general,  inclusive  consciousness. 

With  the  loosening  of  the  bond  with  which  Fechner  had 
connected  ideas  from  the  philosophy  of  nature  with  the 
problem  of  the  measurement  of  sensations,  the  fundamental 


EXPLANATORY  PSYCHOLOGY 


131 


psychophysical  problem  admitting  of  exact  treatment  which 
remained  was  that  of  the  relation  between  the  intensities 
of  sensation  and  stimulus.  The  restriction  of  metric  psy- 
chology to  this  problem  was  the  more  likely  to  lead  to  some 
disappointment  since  the  development  of  Fechner’s  meth- 
ods, which  showed  a tendency  to  approach  the  quantitative 
determinations  of  physics,  rendered  them  more  and  more 
useless  for  the  purposes  of  psychology.1  At  the  same  time 
there  arose  a new  group  of  problems  calling  for  inves- 
tigation according  to  the  new  principles  of  psychical  mea- 
surement. The  course  of  ideas,  the  relation  as  regards 
clearness  of  simultaneous  contents  of  consciousness,  the 
processes  of  recall,  which  formed,  indeed,  the  original  interest 
of  the  science  of  psychical  mechanics  with  its  mathemati- 
cal speculations — all  these  problems  had  to  be  investigated 
anew  by  empirical  methods  as  soon  as  an  exact  basis  for 
psychological  measurement  had  been  discovered.  The  im- 
pulse to  these  investigations  was  given  by  certain  remark- 
able differences  in  temporal  estimation  which  were  notice- 
able in  astronomical  observations  in  the  employment  of  the 
so-called  eye  and  ear  methods.  The  problem  here  is  to 
estimate  the  position  which  a star  passing  through  the 
telescopic  field  occupies  with  reference  to  the  threads  of  a 
micrometer  at  two  successive  strokes  of  a second’s  clock.2 
In  the  year  1795  the  discrepancy  of  eight  tenths  of  a second 
between  the  findings  of  the  London  astronomer  Maskelyne 
and  of  his  assistant  Kinnebrook  led  to  the  dismissal  of  the 
latter.  The  incident  attracted  the  attention  of  the  noted 
astronomer  Bessel,  who  recognized  the  subjective  variations 
in  temporal  estimation  as  a fact  of  general  import  and 
studied  it  somewhat  exhaustively  under  the  name  of  the 

1 Cf.  Chapter  IX,  3,  below. 

2 Cf.  Wirth,  Die  experimentelle  Analyse  der  Bewusstseinsphenomene, 
1908,  pp.  305  /.  and  393. 


132 


HISTORY  OF  PSYCHOLOGY 


personal  equation.  He  sought  a psychological  explanation 
of  the  phenomena  by  bringing  them  into  relation  with  the 
variability  in  the  temporal  succession  of  the  acts  of  hearing 
and  seeing.1  Later  the  phenomena  were  investigated  fur- 
ther with  the  aid  of  artificial  visual  stimuli.  Here  belong 
the  studies  of  Hartmann,2  who  also  interested  himself  in 
the  problem  of  decimal  equations,  i.  e.,  of  the  systematic 
errors  occurring  in  the  estimation  of  the  decimals  of  a lin- 
ear element  which  is  not  further  divided. 

But  even  the  efforts  to  exclude  these  errors  through  an 
objective  method  of  registration  led  to  an  important  psy- 
chological discovery.  Arago,  in  1842,  employed  the  stop- 
watch to  record  the  moment  of  the  passing  of  a star;  later 
the  electrical  contact  key  was  generally  introduced  as  a 
means  of  registration.  The  hope  was  thus  entertained  of 
determining  the  time  of  stellar  passage  with  perfect  accu- 
racy, a hope  which  received  support  from  the  belief  of 
physiologists  of  the  time  that  the  physiological  processes 
involved  in  nerve  conduction  took  place  with  very  great 
rapidity,  a rapidity  about  equal  to  that  of  light.  Neverthe- 
less, the  objective  control  by  means  of  recording  instruments 
still  showed  time  differences,  which  were  thereupon  inter- 
preted as  reaction  times  suited  to  the  special  conditions  of 
such  transit  experiments.3 

Time  differences  of  this  sort  were  also  studied  by  Helm- 
holtz, although  from  a different  point  of  view.  He  started 
with  the  physiological  problem  of  determining  the  rate  of 
conduction  in  the  motor  nerves  of  the  frog,  which  he  found 
to  be  from  30  to  90  metres  a second,  a rate  quite  at  variance 
with  that  assumed  by  earlier  investigators,  including  Johann 
Muller.  The  problem  now  was  to  determine  the  rate  of 

1 Astronomische  Beobacht.  d.  Sternw.  zu  Konigsberg,  Abt.  VIII,  1822, 
XI  and  XVIII. 

2 Grunerts  Archiv  /.  Math.  u.  Phys.,  XXXI,  1858,  p.  24. 

3 Hirsch,  Moleschotts  Untersuchungen,  IX,  1863,  pp.  183  if. 


EXPLANATORY  PSYCHOLOGY 


133 


nerve  conduction  in  man  by  means  analogous  to  those  em- 
ployed by  astronomers  for  the  study  of  individual  differences. 
The  investigations  of  Helmholtz  on  the  subject  are  known 
to  us  through  his  correspondence  with  his  father  during  the 
year  1850.  A hand  movement  was  to  be  made  as  quickly 
as  possible  after  an  electric  signal  was  given.  If  attention 
was  highly  concentrated,  the  time  required  was  one  tenth 
of  a second.  Under  conditions  of  fatigue,  and  if  ideation 
had  to  intervene  before  the  reaction  could  occur,  the  time 
required  was  considerably  longer,  although  still  regular. 
Thus  the  problem  of  time  measurement  which  was  destined 
to  prove  so  fruitful  of  results  was  opened  up  and  was  later 
broadened  in  its  scope  by  the  interpolation  of  psychical 
intermediaries  by  Donders  and  his  pupils.1 

The  different  tendencies  enumerated,  the  theories  of 
perception  of  the  sense  physiologists,  the  psychophysical 
speculations  of  Fechner,  and  the  investigation  of  the  astro- 
nomical registration  errors,  all  alike  pointed  to  the  develop- 
ment of  a new  psychology.  Wundt  treated  them  as  symp- 
tomatic of  a new  experimental  psychology  in  his  Beitrdge 
zur  Theorie  der  Sinneswahrnehmungen  (1862).  He  himself 
penetrated  to  the  very  heart  of  the  problem  of  perception 
by  analyzing  perception  into  its  elementary  psychical 
processes,  by  the  aid  of  the  experimental  method  employed 
in  physiology  rather  than  by  the  aid  of  metaphysical  specu- 
lations. In  an  introductory  section  on  method  he  under- 
takes a general  justification  of  the  experimental  method  in 
psychology.  As  an  illustration  of  an  experiment  which  has 
as  its  object  a purely  psychical  event,  Wundt  cites  the 
artificial  imitation  of  astronomical  observations,  whose  con- 
ditions he  had  himself  varied  by  the  introduction  of  a pen- 


1 De  Jaager,  De  physiologische  Tija  bij  psychischen  Processen,  1865. 
F.  C.  Donders,  “ Die  Schnelligkeit  psychischer  Processe,”  Arch.f.  Anat. 
u.  Physiol.,  1868. 


134 


HISTORY  OF  PSYCHOLOGY 


dular  movement.  The  interpretation  of  the  temporal  dis- 
crepancy of  one  eighth  of  a second  as  a psychical  constant, 
which  could  be  either  positive  or  negative,  was  indeed 
soon  abandoned;  nevertheless,  the  psychological  signifi- 
cance of  the  fact  in  question  was  recognized.  As  a second 
example  is  cited  Fechner’s  law,  which  is  to  be  stated  in  the 
form  of  the  purely  psychological  law:  “Where  two  psychical 
functions  stand  in  immediate  dependence  upon  one  another, 
the  dependent  function  increases  proportionately  as  the 
logarithm  of  the  one  originally  variable,”  a formulation  which 
later  had  to  be  qualified,  but  which  still  retains  its  sig- 
nificance as  an  attempt  at  a purely  empirical  interpreta- 
tion of  Weber’s  law. 

Wundt’s  own  contributions  confine  themselves  to  the  the- 
ory of  sense-perceptions,  the  problem  being  to  trace  the 
genesis  of  sense-perceptions  from  sensation.  The  main  points 
of  the  theories  expounded  in  this  connection,  particularly 
/ that  of  the  relation  of  certain  sense-impressions  and  mus- 
\ cular  movements,  have  had  to  be  restated.  Other  points, 
\ such  as  the  assumption  of  unconscious  logical  processes, 
1 have  had  to  be  abandoned  in  view  of  a more  adequate 
\ knowledge  of  association  processes.1  This  early  sketch, 
however,  was  only  a part  of  a more  general  tendency  in 
I the  direction  of  an  experimentally  grounded  science  of  men- 
tal phenomena,  a science  which  was  destined,  as  Wundt 
himself  had  hoped,  to  become  more  than  an  empty  name. 

With  what  success  the  experimental  method  was  extended 
beyond  the  field  of  sense-perception  to  the  more  complex 
ideational  processes  the  monograph  of  Vierordt,  Uber  den 
Zeitsinn  (1868),  a document  instructive  even  to-day,  bears 
convincing  testimony.  Aside  from  some  investigations  by 
students  of  Vierordt,  the  only  experimental  work  which  pre- 
ceded this  was  that  of  Mach.  The  spirit  of  the  new  method 
1 Cf.  Chapter  XI,  p.  5 (c),  below. 


EXPLANATORY  PSYCHOLOGY 


135 


is  clearly  discernible  in  the  problem  set  by  Vierordt  to  in- 
vestigate experimentally  the  various  functions  and  capaci- 
ties of  the  time-sense,  as  these  are  revealed  in  the  main  sense 
departments,  in  ideal  construction,  and,  finally,  in  the  purely 
conceptual  apprehension  of  temporal  magnitudes.  The  con- 
viction that  these  were  all  signs  of  the  beginning  of  a new 
era  soon  gained  ground.  When  Wilhelm  Windelband  as- 
sumed his  duties  as  professor  of  inductive  philosophy  in 
Zurich  he  was  ready  to  say  that  psychology  had  definitely 
freed  itself  from  the  shackles  of  metaphysics.1  Psychological 
investigations  were  yielding  a fundamental  insight  into  the 
elementary  constitution  of  mental  life,  and  the  study  of  the 
combinations  of  these  elementary  processes  really  constituted 
the  first  beginnings  of  general  psychology.  These  were,  of 
course,  as  he  recognized,  merely  beginnings.  The  question 
why  these  constant  elements  combined  according  to  equally 
constant  and  incomprehensible  laws  is  referred  to  a distant 
future  in  which  a general  metaphysical  theory  of  energy 
would  solve  at  one  stroke  the  most  profound  problem  of 
both  physical  and  mental  phenomena. 

The  life-work  of  Wundt,  who,  as  we  have  seen,  had  early 
voiced  the  demand  for  experimental  psychology,  extends 
into  our  own  time.  He  himself  classified  the  tendencies 
and  the  corresponding  fields  of  labor  of  the  new  psychology 
under  three  general  heads.2  Of  these  the  field  of  sense-per- 
ception admits  most  readily  of  survey.  Here  metaphysical 
and  empirical  hypotheses3  have  in  many  cases  given  way 
to  genetic  theories  which  derive  sense-perceptions  from  the 
elementary  associations  between  simple  sensations.  Thus 
the  concept  of  association,  which  had  during  the  eighteenth 
century  been  wholly  confined  to  memory  processes,  emerged 

1 Tiber  den  gegenwartigen  Stand  der  psychologischen  Forschung,  1876. 

2 “Psychologie,”  in  Die  Philosophie  im  Beginn  des  XX  Jahrhunderts, 
2 ed.,  1907. 

3 Cf.  Chapter  XI,  3 and  4,  below. 


136 


HISTORY  OF  PSYCHOLOGY 


from  under  the  influences  of  sense  psychology  with  a new 
significance  and  scope.  In  this  connection  the  new  principle 
of  original  resultants,  which  asserts  that  a complex  com- 
posed of  psychical  elements  may  be  qualitatively  new  in  the 
sense  that  it  may  show  features  which  were  not  contained 
in  the  original  elements  and  which  could  not  be  obtained 
by  a mere  addition  of  these  elements,  came  to  be  recog- 
nized. Once  this  fact  was  verified  in  the  realm  of  the  sim- 
pler mental  processes  it  was  natural  to  investigate,  from 
the  same  point  of  view,  the  higher  and  more  complex  combi- 
nations, such  as  the  thought  processes  and  imagination. 
Furthermore,  the  methods  of  sense  psychology  came  to  serve 
as  models  for  psychology  as  a whole.  After  the  experimen- 
tal method  had  been  introduced  into  psychology  through 
the  influence  of  sense  psychology,  the  conviction  could  easily 
gain  strength  that  introspection  was  trustworthy  only  when 
subjected  to  experimental  control.  The  simpler  mental  proc- 
esses were,  in  any  case,  accessible  to  methodical  and  sys- 
tematic introspection,  but  quite  recently,  and  often  in  con- 
scious contrast  to  the  older  point  of  view,  the  experimental 
method  has  been  extended  far  beyond  its  original  field  to 
the  most  complex  cognitive  experiences.  It  is  particularly 
the  Wurzburg  school  whose  trust  in  the  reliability  of  con- 
trolled introspection  led  to  the  disappearance  of  the  earlier 
and  more  restricted  conception  of  the  scope  of  the  experi- 
mental method. 

By  the  aid  of  such  systematic  experimental  introspection 
Ach  discovered  forms  of  experience  in  which  a complex  con- 
scious content  was  present  simultaneously  as  knowledge.1 
Imageless  presentation  of  such  a total  knowledge  content 
Ach  called  Beivusstheit,  or  awareness.  Awareness  is  of  two 
kinds,  awareness  of  meaning  and  awareness  of  relation. 

1 N.  Ach,  Uber  die  WillensUUigkeit  und  das  Denken,  1905,  esp.  pp.  210 
jj.  and  235  JJ. 


EXPLANATORY  PSYCHOLOGY 


137 


Since  in  the  awareness  of  meaning  the  felt  presence  of  rela- 
tions on  the  basis  of  excited  reproductive  processes  is  of 
first  importance  for  the  presented  knowledge,  awareness  of 
the  second  order,  like  the  experiences  of  surprise,  confusion, 
and  doubt,  can  also  be  called  awarenesses  of  relation  in  a 
narrower  sense.  In  the  first  case,  the  question  is  one  of 
relation  to  a future  factual  content;  in  the  last,  to  a past 
factual  content.  The  awarenesses  of  the  latter  class  were 
already  known  as  independent  experiences.  We  have  them  in 
Hoffding’s  quality  of  familiarity  {Behanntheitsqualitdt)1  or  in 
Volkelt’s  memorial  assurance  ( Erinnerungsgewissheit ).2  The 
Bewusstseinslage  or  conscious  attitude  of  Marbe  has  been 
interpreted  by  many  as  an  anticipation  of  the  concept  of 
awareness.3  Ach  expressly  distinguished  these  awarenesses 
from  the  phenomena  of  consciousness  commonly  known  as 
presentations  or  ideas.  Awareness,  or  Bewusstheit  in  Ach’s 
sense,  as  simultaneously  presented  knowledge  content,  is  to 
be  distinguished  not  only  from  the  highly  ambiguous  notion 
of  presentation  or  idea,  which  is  sometimes  made  to  include 
even  the  unconscious,  but  also,  and  particularly,  from  image- 
less ideation.  This  imageless  presentation  of  knowledge  is 
a psychical  experience  the  existence  of  which  can  be  demon- 
strated. Nor  is  the  question  one  of  feelings  accompanying 
ideation:  it  is  possible  for  an  awareness  like  surprise,  for 
example,  to  occur  without  any  accompanying  feeling  tone 
whatever.  The  further  question  whether  awareness  and 
feeling  are  not  subdivisions  of  a common  genus  is  still  an 
open  one. 

The  second  field  for  the  labors  of  the  new  psychology  was 

1 Hoff  ding,  “Uber  Widererkennen,  Association  und  psychische  Ak- 
tivitat,”  Vierteljahrsschrift  f.  wiss.  Phil.,  XIII,  1889,  pp.  420  ff. 

2 Zeitschrift  fur  Phil.  u.  phil.  Kritik,  CXVIII,  1901,  pp.  1 ff. 

3 Marbe,  Experimentell-psychologische  Untersuchungen  uber  das  Urteil, 
1901.  Cf.  the  historical  review  of  theories  in  Ach,  Uber  den  Willensakt 
und  das  Temperament,  1910,  p.  18. 


138 


HISTORY  OF  PSYCHOLOGY 


opened  up  by  the  investigations  of  Fechner,  and  its  prob- 
lems are  those  which  have  grown  out  of  the  problem  of 
mental  measurement.  The  fundamental  insight  that  psy- 
chical contents  were  susceptible  to  exact  quantitative  deter- 
mination was  at  first  handicapped  by  Fechner’s  belief  that 
the  stimulus  was  the  measure  of  sensation,  a belief  which 
involved  the  insurmountable  difficulty  of  bringing  two  dis- 
parate realms  into  quantitative  relation.  How  Fechner’s 
point  of  view  became  transformed  into  our  present  point  of 
view  is  a matter  which  must  be  reserved  for  later  discussion.1 
The  recognition  of  the  fact  that  sensations  are  measurable 
only  as  sensations  led  to  a group  of  purely  psychological 
problems,  and  the  subordination  of  psychical  processes  to 
the  concept  of  collective  object  opened  up  to  the  method  of 
measurement  every  field  of  mental  life  in  which  quantitative 
determinations  are  possible.  In  a word,  Fechner’s  psycho- 
physical methods  of  measurement  were  transformed  into 
purely  psychical  methods  of  measurement. 

'While  sense  psychology  and  psychophysics  confined  them- 
selves to  the  investigation  of  the  elementary  facts  of  con- 
sciousness, the  new  psychology  developed  a third  tendency 
which  embraced  the  investigations  of  the  higher  processes  of 
consciousness  and  of  their  general  connections.  After  psy- 
chophysics had  developed  an  exact  and,  at  the  same  time, 
empirical  basis  of  quantitative  determinations  for  a single 
group  of  conscious  contents,  it  was  only  to  be  expected  that 
the  Herbartian  idea  of  mental  mechanics  would  make  its  re- 
appearance. The  conviction,  however,  unmistakably  gained 
ground  that  a mechanics  of  elementary  associations  of  the 
older  style  was  inadequate  to  explain  the  actual  connection 
of  conscious  processes.  Every  act  of  will,  no  matter  how 
simple,  every  fluctuation  in  the  degree  of  clearness  of  con- 
scious contents,  rather  pointed  anew  to  the  fundamental 
1 Cf.  Chapter  IX,  3 and  4,  below. 


EXPLANATORY  PSYCHOLOGY 


139 


fact  of  apperception.  The  Herbartian  psychology  had 
sought  to  reduce  this  concept,  which  was  introduced  into 
philosophy  by  Leibniz,  to  a product  of  association.  Since 
apperception  was  viewed  as  only  a special  case  of  the  fusion 
of  ideas,  its  intimate  relation  to  self-consciousness  and  will 
was  obscured.  The  examination  of  the  complex  processes, 
however,  gave  a new  significance  to  this  concept,  through 
which  the  inner  activity,  immersed  as  it  is  in  the  flow 
of  consciousness,  received  a scientific  expression.  And  thus 
experiment  was  again  proved  to  be  an  aid  to  exact  investi- 
gation.1 

Experimental  psychology,  which  owes  its  birth  almost 
entirely  to  the  German  scientific  spirit  and  investigation, 
soon  passed  beyond  the  boundaries  of  its  native  country. 
It  has  received  its  most  important  development  outside  of 
Germany  in  America.  Previous  to  1880  American  books  on 
psychology  were  written  almost  exclusively  by  theologians 
and  educators.  While  in  Germany  psychology  had  long  been 
the  battle-ground  of  competing  systems  of  speculative  phi- 
losophy, Scottish  realism  held  undisputed  sway  among  the 
older  theological  writers  of  America.  The  earlier  writings 
of  Edwards,2  Hickok,3  and  Porter4  in  the  nineteenth  cen- 
tury are  typical  examples  of  the  species  of  psychology  in 
vogue.  The  attempt  of  Schmucker  to  introduce  into  Ameri- 
can philosophy  the  conception  of  psychology  as  a theory  of 
ideas  received  little  notice.5  The  influences  which  gave 
birth  to  a new  psychology  in  America  were  twofold6  and 
originated  in  Germany  and  England,  respectively.  One  was 
the  experimental  psychology  of  Germany  which  has  been 

1 See  Chapter  VI,  4,  below.  2 Freedom  of  the  Will,  1754. 

3 Hickok,  Empirical  Psychology,  1834;  Rational  Psychology,  1848. 

1 Porter,  The  Human  Intellect,  1868. 

6 S.  S.  Schmucker,  Psychology ; or  Elements  of  a New  System  of  Mental 
Philosophy,  1844. 

6 Cf.  J.  Mark  Baldwin,  “Psychology  Past  and  Present,”  Psych.  Rev., 
I,  1894,  pp.  363  ff. 


140 


HISTORY  OF  PSYCHOLOGY 


discussed  in  the  previous  pages.  The  other  was  the  tra- 
ditional doctrine  of  English  associationism  and  Spencer’s 
notion  of  evolution  or  development.  To  a certain  degree, 
this  twofold  origin  is  still  commemorated  in  the  controversy 
between  the  associationists  and  the  apperceptionists. 


PART  11 


DEVELOPMENT  OF  THE  FUNDAMENTAL 
CONCEPTS  OF  PSYCHOLOGY 

CHAPTER  V 

THE  IDEA  OF  PSYCHOLOGY  AS  A SCIENCE 

The  history  of  an  empirical  science  shows  not  merely 
a growth  of  empirical  materials  but  also  a transformation, 
which  is  not  less  significant,  in  the  fundamental  principles 
employed  in  the  interpretation  of  these  ma^rials.  This 
transformation  is  observable  even  when  the  alleged  self- 
evidence of  the  principles  in  question  precludes  an  histor- 
ical development.  The  history  of  mechanics,  for  example, 
shows  how  so  obvious  a principle  as  that  of  inertia  has  only 
comparatively  recently  supplanted  other  principles  which 
were  seen  to  be  inadequate.  But  even  this  principle,  to- 
gether with  others  which  were  for  a long  time  accepted  as 
self-evident,  has  even  quite  recently  been  held  to  be  a purely 
empirical  principle  which  would  tend  to  break  down  under 
radically  altered  conditions,  with  the  introduction  of  veloci- 
ties, for  example,  approximating  that  of  light.  The  subject- 
matter,  however,  of  these  sciences  remains  the  same;  and 
if  one  should  speak  of  a change  in  chemical  elements,  for 
example,  in  virtue  of  which  chemistry  would  become  an 
historical  science  in  the  widest  sense,  one  must  remember 
that  the  development  has  been  so  extremely  slow  here  that 
it  can  be  practically  disregarded  in  writing  the  history  of 
chemistry. 


141 


142 


HISTORY  OF  PSYCHOLOGY 


The  case  of  the  history  of  philosophy  is  different.  Among 
the  many  influences  which  converge  here,  one  of  the  most 
important  is  that  of  personal  experience.  Personal  experi- 
ence, to  be  sure,  plays  its  part  everywhere,  but  in  the  philo- 
sophical sciences  we  become  so  uniquely  aware  of  its  influ- 
ence that  the  history  of  philosophy  can  be  defined  outrightly 
as  a history  of  philosophical  experiences.  And  these  experi- 
ences have,  in  the  course  of  time,  changed  their  character. 
Although  the  central  problems  of  philosophy  can  be  traced 
throughout  thousands  of  years  of  reflective  thought,  the 
experiences  themselves  which  give  rise  to  a given  philo- 
ophical  problem  have  become  different. 

Psychology  shows  both  forms  of  historical  development. 
It  deals  with  experiences  as  its  special  subject-matter,  but 
it  does  so  as  an  empirical  science.  Here  we  have  to  deal, 
then,  with  Ganges  both  in  fundamental  principles  and  in 
the  subject-matter  itself.  In  the  history  of  psychology,  to 
be  sure,  the  principles  of  explanation  do  not  appear  with  the 
same  clearness  as,  for  example,  the  principles  of  explana- 
tion in  mechanics.  Nevertheless,  it  is  noticeable  that  many 
ideas  which  are  regarded  as  generally  valid  by  psycholo- 
gists of  to-day  were  formerly  unknown.  An  example  of 
this  would  be  the  notion  of  the  analyzability  of  complex 
mental  contents  into  their  elements. 

Of  greater  difficulty  is  the  question  in  what  sense  expe- 
riences undergo  changes,  thus  producing  changes  in  the 
subject-matter  of  psychology.  T ist  as  it  is  possible  for  an 
individual  to  put  himself  ba  ^ into  an  earlier  period  of 
his  life  and  to  recognize  it  as  belonging  to  himself,  with- 
out actually  re-experiencing  the  emotional  excitements  and 
motives  in  the  form  of  their  previous  occurrence,  so  it  is 
possible  for  a similar  difference  to  exist  between  the  con- 
scious experiences  of  people  removed  from  each  other  by 
thousands  of  years.  This  question  need  not,  however,  be 


PSYCHOLOGY  AS  A SCIENCE 


143 


dealt  with  here,  since  psychology,  in  so  far  as  it  is  not  indi- 
vidual psychology,  confines  itself  to  phenomena  of  general 
scope  and  significance.  And  it  is  certain  that  the  elements 
of  mental  life  and  the  general  forms  of  their  combination 
have  undergone  little  or  no  change  within  the  historical 
period.  If  the  physiological  characteristics  of  man  have 
undergone  no  change  within  historical  times,  it  is  certain 
that  no  changes  have  occurred  in  the  psychological  func- 
tions either.  The  hypothesis  of  the  color-blindness  of  the 
ancient  Greeks,  for  example,  has  not  stood  the  test  of  critical 
examination.  There  is  just  as  little  proof  of  the  assumption 
that  the  number  of  sensation  qualities  in  any  sense  depart- 
ment, or  that  simple  reaction-time,  or  any  other  essential 
attribute  of  such  mental  processes  which  can  be  rendered 
precise  by  the  aid  of  psychophysical  constants,  has  under- 
gone alteration.  We  do,  indeed,  find  considerable  variation 
in  the  nomenclature  of  sensation  qualities.  Although  the 
discriminable  sensation  qualities  in  the  higher  sense  depart- 
ments were  determined  with  considerable  unanimity  at  an 
early  period  in  the  history  of  psychology,  we  find  the  most 
diverse  opinions  concerning  those  of  the  lower  senses  as  late 
as  the  nineteenth  century.  Gruithuisen,1  for  example,  dis- 
tinguished fourteen  qualities  of  gustatory  sensations,  while 
Valentin2  recognized  only  two,  sweet  and  bitter.  However, 
the  divergence  of  opinion  here  is  probably  due  merely  to  the 
difficulties  of  psychological  analysis.  The  case  of  the  feel- 
ings is  of  a similar  nature'  If  differences  of  opinion  exist 
here,  we  may  be  sure  thafiothere  has  never  been  a time 
when  such  differences  did  not  exist. 

Although  introspective  observation  has  been  much  facili- 
tated and  refined  by  the  greater  differentiation  of  mental 
life  which  has  occurred  in  connection  with  the  progress 


\ 


1 Anthropologie,  1810,  p.  312. 

2 Grundriss  der  Physiologie  des  Menschen,  2d  ed.,  1847. 


144 


HISTORY  OF  PSYCHOLOGY 


of  intellectual  culture,  the  realm  of  elementary  experiences 
with  which  introspection  deals  has  remained  the  same.  This 
change  in  complex  experiences  which  the  history  of  civiliza- 
tion illustrates  is,  therefore,  not  of  immediate  interest  for  the 
history  of  psychology.  We  do,  indeed,  occasionally  find  a 
reflex  influence  of  complex  experiences  upon  the  conception 
of  the  elementary  experiences,  the  significance  of  an  experi- 
ence thus  becoming  of  decisive  importance  for  the  structure 
of  this  experience  itself. 

Olt  is  one  of  the  most  noteworthy  characteristics  in  the 
history  of  psychology  that  the  nature  of  a psychical  event  is 
often  determined  by  the  nature  of  the  object  upon  which 
the  idea  or  the  desire  implied  in  this  event  is  directed.  That 
which  can  think  an  eternal  truth  is  itself  eternal;  that  which 
occupies  itself  with  sense-impressions  is,  like  the  latter, 
transient  and  perishable.  This  is  the  presupposition  which 
led  Plato  to  the  division  of  man’s  inner  life  into  a higher  and 
a lower  part  and  which  was  confirmed  by  a very  analogous 
distinction  within  the  ethical  field.  If  modern  psychology 
describes  conscious  experiences  as  a perpetual  flux  of  psychic 
processes  which  preserves  its  continuity  amid  its  changing 
aspects  or  phases,  it  does  so  only  at  the  end  of  a long,  sub- 
jectifying process.  While  in  the  natural  sciences  subjective 
factors  have  been  reduced,  a similar  process  of  reduction 
has  occurred  in  psychology,  only  in  an  opposite  direction. 
We  are  acquainted  with  the  process  of  empathy  ( Einfiih - 
lung)  in  which  psychic  contents  are  experienced  as  connected 
with  objective  contents.  But  there  is  also  the  opposite 
process  in  which  a relationship  is  experienced  between  psy- 
chic states  and  the  objects  to  which  they  refer. 

In  so  far  as  we  have  an  objectification  of  experiences  in 
the  process  of  empathy,  the  results  of  such  a process  have 
been  largely  invalidated  by  the  presuppositions  of  modern 
science  since  the  beginnings  of  scientific  reflection.  The  sec- 


PSYCHOLOGY  AS  A SCIENCE 


145 


ond  form  of  objectification,  the  transference  of  the  charac- 
teristics of  objects  to  experiences,  with  which  we  have  here 
to  do,  extends  to  a period  lying  within  the  history  of  psy- 
chology. Just  as  we  can  live  over  again  the  state  of  mind 
of  a primitive  man  who  peopled  the  winds  and  the  clouds, 
we  can  in  imagination  transport  ourselves  into  the  mental 
condition  of  one  who  in  the  contemplation  of  supernatural 
objects  feels  himself  as  being  another.  But  the  true  inward- 
ness of  this  experience  we  are  able  to  judge  only  from  its 
results. 

The  presupposition  mentioned,  particularly  in  the  form 
of  the  theory  of  an  ontological  affinity  between  that  which 
knows  and  that  which  is  known,  has  been  from  the  earliest 
times  one  of  the  riding  ideas  of  various  systems  of  meta- 
physical psychology.  We  find  it  as  a common  element  in 
the  two  great  philosophical  rivals  of  ancient  Greece,  Plato 
and  Democritus.  Both  alike  find  within  experience  a cer- 
tain kind  of  knowledge  having  the  character  of  intuitive 
certainty,  which  points  beyond  the  appearances  of  sense, 
'yvcofir]  71/770-177.  With  both  thinkers  the  content  of  this 
knowledge  is  the  forms  of  reality  ( ISeai ).  According  to 
Plato,  however,  the  soul  can  know  the  eternal  ideas  because 
it  is  coeternal  with  them  and  remembers  them  from  asso- 
ciation with  them  in  a previous  state  of  existence.  In 
Democritus  the  ISeat  are  the  geometrical  forms  of  the 
atoms,  and,  since  the  soul  itself  consists  of  atoms,  it  knows 
objects  from  the  minute  images  (I'StaAa)  expressing  the  na- 
ture of  the  atoms  which  penetrate  the  soul.  These  meta- 
physical interpretations  do,  indeed,  pass  far  beyond  the  range 
of  psychology.  Their  common  presupposition,  however,  is 
that  of  the  identity  between  the  content  of  knowledge  and 
its  bearer,  between  object  and  subject.  If  this  presupposi- 
tion lapsed  in  the  later  and  more  genuine  analysis  of  con- 
sciousness, this  was  due  not  only  to  the  changed  point  of 


146 


HISTORY  OF  PSYCHOLOGY 


view  from  which  experiences  were  regarded  but  also  to 
alterations  in  the  experiences  themselves.  The  elabora- 
tion of  conceptual  ways  of  thinking  tended  to  accentuate 
the  cognitive  aspects  of  experience,  a process  analogous  to 
the  heightening  of  ecstatic  experience  with  which  the  belief 
in  immortality  was  connected.1  If  we  assume  that  intel- 
lectual experiences  have  lost  this  character  of  vivacity  in 
the  development  of  scientific  thought,  then  the  subject- 
matter  of  psychology,  the  experiences  themselves,  would, 
indeed,  have  undergone  some  change  within  the  history  of 
psychology. 

Aside,  however,  from  these  details,  what  conditions  the 
development  of  fundamental  psychological  concepts  is  not 
so  much  an  alteration  in  the  experiences  as  a development 
in  the  point  of  view  from  which  psychical  facts  are  regarded. 
Perhaps  it  is  true  that  psychology  has  been  less  successful 
in  penetrating  to  the  facts  which  are  removed  from  the 
ordinary  realm  of  experience  than  the  other  sciences.  This 
is  compensated  for,  however,  by  the  greater  change  in  the 
point  of  view  from  which  mental  processes  are  regarded. 
In  the  chapters  which  follow  we  shall  try  to  state  the  more 
salient  features  of  this  development.  In  addition  to  the 
consolidation  of  the  concept  of  a science  of  psychology 
there  arises  a gradual  apprehension  of  the  subject-matter 
of  psychology — namely,  consciousness.  The  different  views 
as  to  what  are  the  fundamental  phenomena  of  consciousness 
appear  in  the  attempts  at  a classification  of  mental  proc- 
esses. No  less  have  the  methods  of  psychology  shared  in 
these  changes  in  point  of  view.  Among  the  theoretical  con- 
cepts, finally,  one  of  the  most  important  is  the  concept  of 
psychical  measurement  which  has  in  modern  times  become 
fundamental  for  psychology,  aiming  at  exact  quantitative 
determinations. 


1 Cf.  p.  16. 


PSYCHOLOGY  AS  A SCIENCE 


147 


The  development  of  the  concept  of  psychology  takes  its 
start  from  the  older  conceptual  determinations  of  psychology, 
originating  within  the  framework  of  one  or  the  other  of  the 
various  philosophical  systems.  The  problem  of  psychology 
as  a science,  which  contained  the  motives  out  of  which  the 
modern  concept  of  psychology  developed,  is  of  comparatively 
recent  origin. 

i.  Older  Conceptual  Formulations  of  Psychology  ' . 

Since  the  concept  of  psychology  as  a science  has  become  a 
problem  only  in  comparatively  modern  times,  the  preceding 
conceptual  determinations  of  psychology  corresponding  to 
the  general  tendencies  of  psychological  thought  lose  some- 
thing of  their  significance.  The  word  psychology  does  not 
occur  previous  to  the  sixteenth  century.  Melanchthon  em- 
ployed the  term  as  a title  of  academic  lectures.  R.  Gockel 
used  it  in  1590  as  a collective  title  for  the  works  of  va- 
rious authors.  The  term  became  generally  known  through 
Christian  Wolff,  who  did  so  much  for  the  establishment  of 
philosophical  terminology.  Up  to  Wolff’s  time  the  term 
psychosophy,  apparently  introduced  by  J.  J.  Becker,  seems 
to  have  been  in  use.  The  term  pneumatology  is  also  found 
in  the  writings  of  Leibniz. 

If  we  should  attempt  to  review  the  older  conceptual  formu- 
lations, we  should  find  in  the  celebrated  ars  magna  of  Ray- 
mond Lullus,  who  lived  in  the  latter  half  of  the  twelfth  cen- 
tury, a special  figura  ammoe  which  purports  to  represent 
the  whole  of  psychology.  The  soul  ( S ) was  symbolized  by 
a quadrilateral  figure.  The  three  principal  faculties,  mem- 
oria,  intellectus,  and  voluntas,  are  designated  by  the  letters 
B,  C,  and  D at  three  corners  of  the  figure,  while  the  fourth 
corner  was  lettered  E and  represented  the  unity  of  the 
faculties.  This  relation  was  represented  by  the  formula, 


148 


HISTORY  OF  PSYCHOLOGY 


B + C + D — E.  Above  this  figure  are  superimposed  similar 
squares  which  turn  upon  the  same  centre,  at  whose  corners 
other  faculties  are  represented  by  letters,  as  memoria  obliviens 
( K ),  intelledus  ignorans  (L),  voluntas  diligens  vel  odiens  (M); 
whence  K-\-  L-\-M=N , a new  condition.  Four  such  for- 
mulas are  required  to  represent  the  complete  nature  of  the 
soul.  About  this  whole  figure  revolves  a second  concentric 
one,  so  that  we  get  in  all  one  hundred  and  thirty-six  cameras 
(, secunda  figura  S ).  The  great  esteem  in  which  the  art  of 
Lullus  was  held  illustrates  the  tendency  to  formalism  which 
has,  perhaps,  never  been  developed  to  the  same  point  as  in 
the  philosophy  of  Scholasticism.  If  problems  could  be  set 
and  answered  by  shifting  these  concentric  figures,  it  is 
merely  a naive  expression  of  the  fact  that  in  the  conceptual 
world  every  correctly  formulated  problem  has  some  solu- 
tion. We  know  that  in  mathematics  or  pure  logic,  for 
example,  where  we  have  to  do  with  ideal  objects,  any  cor- 
rectly stated  problem  can  be  solved,  although  the  solution 
might  not  be  explicitly  statable.  Once  having  ascertained 
the  significance  of  the  symbols  we  employ,  we  operate  with 
these  in  a purely  mechanical  fashion.  It  is  in  some  such 
manner  that  we  might  explain  the  great  vogue  of  the  Lullian 
system,  although  it  was  bound  to  be  shattered  by  the  impact 
of  modern  science,  so  great  was  the  discrepancy  between 
this  mechanical  method  of  juggling  concepts  and  the  empiri- 
cal order  it  purported  to  represent. 

The  views  which  have  been  held  at  various  periods  regard- 
ing the  question  of  psychology  as  a science  are  clearly 
reflected  in  the  position  assigned  to  psychology  in  the  more 
important  attempts  at  the  classification  of  the  sciences.  In 
Bacon’s  classification  psychology  is  defined  as  philosophy  of 
the  soul  ( jphilosophia  humana  circa  animam )}  It  is  divided 
into  a doctrina  de  spiraculo  and  a doctrina  de  anima  sensibili, 
1 De  dig.  et  augm.  scient.,  1623,  IV,  3. 


PSYCHOLOGY  AS  A SCIENCE 


149 


hive  producta.  This  branch  of  philosophy  is  further  divided 
into  a doctrine  of  the  substance  and  faculties  of  the  soul 
and  a doctrine  of  the  use  and  the  objects  of  these  faculties. 
The  faculties  of  the  sensible  soul  are  those  of  movement 
and  sensation.  In  his  distinction  between  the  divine  and 
the  earthly  soul  Bacon  follows  closely  the  example  of  Aris- 
totle. Among  the  faculties  of  the  soul  are  also  named  sooth- 
saying and  witchcraft  ( divinatio  and  fascinatio),  which  are 
regarded  as  practical  applications  of  psychology.  Speaking 
broadly,  then,  we  find  Bacon’s  conception  of  psychology  in- 
cluding the  traditional  views  of  metaphysical  and  faculty 
psychology,  although  it  must  be  conceded  that  the  division 
of  the  science  of  the  phenomena  of  human  life  was  con- 
tinued pretty  largely  unchanged  in  the  much  later  division 
into  physiology  and  psychology. 

The  division  of  psychology  on  the  basis  of  faculties  is  also 
found  in  D’Alembert,  who  was  the  first  to  undertake  a classi- 
fication of  the  sciences  similar  to  Bacon’s.1  The  funda- 
mental faculties  recognized  by  him  are  intelligence  and  will, 
the  object  of  the  former  being  the  true,  that  of  the  latter 
the  good.  The  former  gives  rise  to  the  problem  of  logic,  the 
latter  to  the  problem  of  morals.  Since  D’Alembert  derives 
the  different  sciences  from  the  different  objects  toward 
which  the  various  sciences  are  directed,  psychology  again 
becomes  subordinated  to  the  normative  sciences  of  logic  and 
ethics. 

Our  source  of  information  concerning  the  general  concep- 
tion of  psychology  developed  at  this  time  is  the  article 
“Psychology,”  in  Diderot’s  Encyclopedic.  Psychology  is 
here  viewed  as  a branch  of  philosophy  which  defines  the 
nature  of  the  human  soul  and  gives  an  account  of  its  activi- 
ties. It  divides  into  empirical  or  experimental  and  rational 


1 Explication  detaillee  du  systeme  des  connaissances  humaines,  1752, 
CEuvres,  1821,  I,  pp.  102  jj. 


150 


HISTORY  OF  PSYCHOLOGY 


psychology.  According  to  Diderot,  empirical  psychology  is 
more  important  than  rational  psychology  and  furnishes  the 
starting-point  for  the  latter. 

Neither  of  the  definitions  mentioned  is  very  definitely 
motived  and  must,  of  course,  not  be  measured  by  a stand- 
ard which  developed  only  after  the  possibility  of  scientific 
psychology  became  itself  a problem. 

2.  The  Problem  of  a Science  of  Psychology 

The  understanding  of  the  requirements  of  a scientific  psy- 
chology was  for  a long  time  retarded  on  account  of  the  fact 
that  psychology  was  regarded  as  sufficiently  defined  as  the 
science  of  the  soul,  and  it  was  scientific  only  in  so  far  as  this 
was  possible  within  the  limits  set  by  the  metaphysical  pre- 
suppositions regarding  the  nature  of  the  soul.  Only  when 
psychology  became  an  independent  empirical  science  could 
the  question  of  its  scientific  concept  arise.  This  question 
reduced  to  the  alternative  as  to  whether  psychology  was  in 
the  last  resort  a species  of  metaphysics  or  of  physics.  In 
consequence  of  this  alternative,  psychology  divided  into  two 
branches.  This  partition  occurred  in  the  eighteenth  cen- 
tury, when  empirical  psychology  was  in  some  quarters  re- 
garded as  a branch  of  physics,  while  the  older  Leibniz- 
Wolffian  school  adhered  to  the  position  that  it  belonged  to 
metaphysics. 

The  profounder  study  of  the  scientific  character  of  psy- 
chology on  the  part  of  Kant,  whose  psychological  thought 
was  otherwise  largely  traditional,  was  of  real  significance  for 
the  development  of  the  science.  The  distinction  between 
rational  and  empirical  psychology  Kant  is  generally  believed 
to  have  inherited  from  Wolff.1  Wolff,  however,  deduced  the 
unity  and  the  simplicity  of  the  soul  ontologically  from  the 
1 Cf.  J.  B.  Meyer,  Kants  Psychologie,  pp.  220  ff. 


PSYCHOLOGY  AS  A SCIENCE 


151 


simplicity  of  substance,  while  Kant  arrived  at  the  idea  of 
the  soul  as  a simple  and  unitary  substance  from  the  unity 
and  simplicity  of  consciousness.  It  is  an  extreme  position 
to  maintain  with  Herbart  that  Kant’s  idea  of  rational  psy- 
chology was  picked  out  of  the  air.  A more  circumspect 
historical  investigation  rather  shows  that  the  Kantian  for- 
mulation of  rational  psychology  wras  derived  from  the  study 
of  Knutzen,  Mendelssohn,  and  Reimarus.  Rational  psy- 
chology, as  expounded  by  Kant,  was  literally  a preoccupa- 
tion of  the  period.  After  the  rejection  of  the  paralogisms 
of  rational  psychology,  nothing  remained  for  Kant  but 
empirical  psychology.  The  investigations  of  such  an  empir- 
ical psychology  constituted  for  Kant  a field  completely  dis- 
tinct from  his  own  critical  task  of  discovering  the  a priori 
elements  in  metaphysics,  logic,  and  ethics.  It  is  important 
to  notice  this,  since  experience,  in  the  sense  of  Kant,  is  the 
joint  product  of  the  material  of  sensation  and  of  the  sub- 
jective forms  of  knowledge,  and  since  investigations  of  the 
nature  of  this  experience  would  seem  inevitably  to  become 
psychological  in  character.  Nevertheless,  epistemological 
reflection  must  be  distinguished  from  the  observation  of  the 
empirical  mental  facts.  The  former  reveals  the  a priori 
constituents  of  experience,  the  latter  the  general  laws  of 
mental  life.  Kant  draws  here  an  extremely  important  dis- 
tinction, which  has  been  wrongly  interpreted  by  certain  rep- 
resentatives of  modern  Neo-Kantianism  as  the  subordi- 
nation of  empirical  psychology  to  the  primary  problem  of 
epistemology.1 

Kant  denied  the  possibility  of  systematic  analysis  in  psy- 
chology on  the  ground  that  the  manifold  of  inner  observa- 
tion could  only  be  separated  mentally  but  could  not  be  held 
in  separation  nor  recombined  at  will.2  His  second  objection 

1 Cf.  3 (a),  below. 

2 Metaphysische  Anfangsgriinde  der  Naturwissenschaft,  Vorrede,  1786. 


152 


HISTORY  OF  PSYCHOLOGY 


has  become  better  known.  It  was  to  the  effect  that  psy- 
chology could  never  become  an  explanatory  science  since 
it  did  not  admit  of  mathematical  treatment.  The  only 
possibility  would  be  to  apply  the  law  of  constancy  to  the 
flux  of  inner  changes.  But  we  do  not  attribute  to  the  soul 
anything  a 'priori,  except  that  it  has  temporal  duration,  and 
with  the  pure  intuition  of  time  we  are  unable  to  construct 
anything,  as  we  can  with  the  intuition  of  space,  since  it  has 
only  one  dimension.  Kant  follows  out  the  same  idea  in  the 
criticism  of  rational  psychology,  which  connects  itself  with 
the  paralogisms  of  pure  reason.  Rational  psychology  is  the 
attempt  to  obtain  synthetic  knowledge  a priori,  such  as  is 
obtained  from  the  bare  concept  of  an  extended,  impenetrable 
being,  in  the  theory  of  bodies.  But  time,  as  the  only  form 
of  inner  intuition,  can  give  us  knowledge  only  of  the  change 
in  the  determinations  of  an  object,  never  of  the  object  itself 
which  is  determined.  The  ego  would  have  to  be  an  intuition 
or  a concept  of  an  object  in  order  to  yield  rational  knowl- 
edge of  the  nature  of  a thinking  being,  whereas  it  is  in 
reality  merely  the  form  of  consciousness. 

Kant,  accordingly,  thought  very  slightingly  of  the  future 
of  scientific  psychology  although  he  regarded  its  develop- 
ment in  the  direction  of  empirical  anthropology  as  very 
important.  Empirical  psychology  finds  its  object  in  the 
ego,  as  object  of  inner  experience,  or  as  phenomenon  of  the 
inner  sense,  and  thus  becomes  anthropology  or  a sort  of 
physiology  of  the  inner  sense.  The  relation  of  the  inner 
sense  to  time,  however,  unavoidably  produces  uncertainty 
in  empirical  psychology  which  depends  upon  the  deliver- 
ances of  the  inner  sense.  And  since  the  presuppositions 
necessary  for  an  experimental  psychology  are  not  met,  psy- 
chology has  to  content  itself  with  being  a systematic  nat- 
ural history  of  the  inner  sense. 

There  are  several  reasons  for  Kant’s  unfavorable  opinion 


PSYCHOLOGY  AS  A SCIENCE 


153 


of  psychology.  One  has  to  remember,  in  the  first  place,  the 
state  of  empirical  psychology  at  the  time.  Kant’s  dispar- 
agement of  contemporary  psychologists  and  of  their  uncon- 
vincing explanations  is  everywhere  apparent.1  The  only 
writer  of  whom  he  expected  anything  considerable  was 
Tetens,  whose  principal  psychological  work,  Philosophische 
Versuche  iiber  die  menscliliche  Natur,  as  we  learn  from  a 
letter  of  Hamann’s  to  Herder,2  was  constantly  before  him. 
The  problem  of  freedom  proper,  however,  Kant  writes  to 
M.  Herz,  Tetens  leaves  entirely  unsolved.  The  deeper 
reason,  however,  lies  in  the  demands  which  Kant  makes  of 
knowledge;  he  demands  apodictic  certainty  of  a science  in 
the  strict  sense  of  the  word.  A consciousness  of  uncondi- 
tioned necessity  can  only  be  derived  from  the  necessary 
conditions  of  our  thought,  and,  since  these  do  not  obtain 
within  the  realm  of  empirical  psychology,  Kant  felt  obliged 
to  deny  to  the  latter  the  rank  of  a science. 

Notwithstanding  Kant’s  opinion,  however,  the  history  of 
psychology  shows  many  attempts  to  apply  mathematics  to 
psychology,  among  which  the  Herbartian  psychology  ranks 
supreme.  The  very  branch  of  psychology  concerning  whose 
future  Kant  had  the  most  serious  misgivings  became  one  of 
the  most  popular  in  the  nineteenth  century. 

Although  Herbart’s  speculations  contained  many  unten- 
able presuppositions,  his  method  of  regarding  the  intensity 
of  ideas  in  its  relation  to  time  is  nevertheless  based  upon  an 
incontestable  formal  condition  of  the  mathematical  treat- 
ment of  psychical  phenomena.  The  fact  that  the  intensity 
of  psychical  processes  constitutes  a dimension  in  addition  to 
that  of  time  has  been  felt  even  by  psychologists  who  do  not 
share  the  conclusions  of  Herbart — men  like  Wundt,  for 
example— as  a weakening  of  the  Kantian  objection.  Even 

1 Cf.,  for  example,  Philosophie  als  Wissenschaft,  1794. 

2 May  7,  1779. 


154 


HISTORY  OF  PSYCHOLOGY 


more  sweeping  is  the  position  of  Brentano,1  who  insisted  upon 
the  indispensability  of  mathematics  in  the  exact  treatment 
of  any  science  on  the  ground  that  we  come  upon  quantities 
in  literally  every  field  of  phenomena.  If  there  were  no  in- 
tensities in  the  realm  of  psychical  phenomena,  the  theories 
of  psychology  would  be  essentially  simpler  but  not  less 
exact  than  now. 

Comte  defended  the  possibility  of  the  science  of  psychology 
from  different  points  of  view.  Psychology,  as  we  know,  was 
not  included  in  the  linear  arrangement  of  the  sciences  of 
which  Comte  was  the  author.  In  his  Positive  Philosophy  the 
psychological  material  is  included  under  the  general  head  of 
biology.  According  to  Comte,  psychology,  up  to  the  time 
of  Gall,  remained  entirely  excluded  from  the  great  scientific 
movement  originated  by  Descartes.  The  positive,  that  is, 
the  purely  scientific,  doctrine  of  the  affective  and  intellectual 
functions  “consists  in  the  experimental  and  rational  study 
of  the  phenomena  of  inner  sensibility  belonging  to  the  cere- 
bral ganglia  which  exist  apart  from  all  external  apparatus.”  2 
Since  it  is  impossible  to  observe  mental  processes  during 
their  occurrence,  psychology  based  upon  introspection  must 
give  way  to  phrenological  physiology  in  the  sense  of  Gall. 

Owing  to  its  obvious  misunderstanding  of  the  simplest 
facts  of  consciousness,  the  teaching  of  Comte  did  not  mate- 
rially influence  the  history  of  psychology,  and  has  conse- 
quently remained  somewhat  isolated.  That  this  displace- 
ment of  the  conception  of  psychology  was  not  by  any  means 
immanent  in  the  positivistic  arrangement  of  the  sciences  is 
shown  by  the  classification  of  Herbert  Spencer,  which  is  in 
many  respects  similar  to  Comte’s,  and  in  which  psychology 
is  included  as  an  independent  science  following  upon  biology, 
and  preparatory  to  sociology.  The  influence  of  Spencer’s 

1 Psychologie  v.  empirischen  Standpunkt,  I,  1874,  p.  86. 

2 English  translation  by  H.  Martineau,  bk.  V,  chap.  VI. 


PSYCHOLOGY  AS  A SCIENCE 


155 


metaphysical  presuppositions  is  evident  in  his  view  of  all 
contents  of  consciousness  as  modifications  of  an  ultimately 
unknowable  spiritual  substance;  and  in  his  division  of  psy- 
chology into  objective  and  subjective  psychology,  the 
former  exhibiting  mental  states  in  their  relations  to  the 
stages  of  organic  evolution,  the  latter  deriving  the  simple 
elements  by  the  analysis  of  the  highest  psychical  phenomena, 
namely,  the  thought  processes,  we  see  the  influence  of  his 
philosophical  theory  that  all  mental  activity  represents  a 
differentiation  and  integration  of  states  of  consciousness. 

3.  The  Modern  Concept  of  Psychology 

In  the  controversies  regarding  the  modern  conception  of 
psychology  the  old  question  whether  psychology  is  meta- 
physics or  physics  returns  in  a new  form.  Psychology  was 
obliged  once  more  to  come  to  terms  with  philosophy  and 
with  natural  science.  Only  the  roles  were  now  inter- 
changed. The  question  now  was  not  whether  psychology 
was  a philosophical  discipline  but  the  opposite,  whether 
certain  philosophical  disciplines  were  not  rather  to  be  re- 
garded as  branches  of  psychology.  As  regards  the  relation 
of  psychology  to  natural  science,  with  which  psychology  was 
seen  to  have  many  methods  in  common,  the  problem  here 
was  to  define  the  boundaries  of  the  subject-matter  which 
rightfully  fell  to  psychology. 

The  relation  of  psychology  to  philosophy  was  worked  out 
in  connection  with  the  movement  known  as  psychologism. 
The  task  of  relating  psychology  to  natural  science  led  to 
establishment  of  criteria  according  to  which  the  contents 
of  experience  were  to  be  divided  into  physical  and  mental 
phenomena. 


156 


HISTORY  OF  PSYCHOLOGY 


(a)  Psychology  and  Philosophy:  Psychologism  and  Its 
Opponents 

Since  J.  E.  Erdmann  the  term  psychologism  has  been 
applied  to  the  view  that  psychology  is  auxiliary  to  and  the 
basis  of  the  various  mental  sciences.  This  position  of  psy- 
chology in  the  hierarchy  of  the  sciences  most  modern  psy- 
chologists would  probably  accept  as  an  expression  of  the 
scientific  temper  of  the  time.  In  the  narrower  sense,  how- 
ever, psychologism  means  the  view  that  reality  is  composed 
of  psychical  contents  and  that  the  various  branches  of 
mental  science,  particularly  philosophy,  are  accordingly 
nothing  else  than  psychology.  The  sole  task  of  philosophy 
is  thus  to  make  a psychological  analysis  of  the  content  of 
experience.  Of  the  different  varieties  of  psychologism  it  is 
the  epistemological  variety  in  the  form  expounded  by  John 
Stuart  Mill  that  has  been  most  widely  discussed. 

Arguments  for  or  against  a psychological  tendency  in 
epistemological  questions  had,  of  course,  been  current  before 
Mill’s  time.  Kant  had,  in  substance,  taken  a stand  against 
psychologism  when  he  distinguished  the  psychological  ex- 
planation of  judgment  from  its  validation.1  Beneke,  on  the 
other  hand,  was  not  less  emphatic  than  later  epistemological 
psychologism  in  proclaiming  psychology  as  the  basis  of  the 
whole  of  philosophy.  In  modern  times  the  discussion  has 
centred  around  the  influential  empirical  logic  of  John  Stuart 
Mill. 

In  his  controversy  with  Sir  William  Hamilton,  Mill  held 
scientific  logic  to  be  a part  or  branch  of  psychology.2  Its 
normative  character  consists  merely  in  the  fact  that  it  is  a 
practical  art  rather  than  a pure  science.  In  the  dispute 
over  psychological  logic,  which  thus  became  the  centre  of 

1 Uber  Philosophic  uberhaupt,  p.  167. 

2 An  Examination  of  Sir  William  Hamilton's  Philosophy,  5th  ed.,p.461. 


PSYCHOLOGY  AS  A SCIENCE 


157 


the  controversy,  the  distinction  between  the  ideal  character 
of  purely  logical  laws  and  the  empirical  character  of  psy- 
chological laws  was  brought  out  with  illuminating  distinct- 
ness, as,  for  instance,  in  Sigwart’s  excellent  Logik  (1873-8), 1 
which,  however,  again  made  concessions  to  psychologism  in 
the  doctrine  of  the  twofold  character  of  the  fundamental 
laws  of  logic  as  at  once  natural  laws  and  normative  laws  of 
thought.  Nevertheless,  there  seems  to  be  a growing  rec- 
ognition of  the  fact  that  the  general  conditions  of  the 
objects  of  thought  which  logic  investigates  are  of  a different 
nature  from  the  thought  processes  which  belong  to  psy- 
chology, a distinction  which  underlies  a fundamental  dif- 
ferentiation of  the  respective  tasks  of  logic  and  psychology.2 
Psychology  would  be  interested,  as  Windelband  says,  to 
determine  how  an  idea  arises;  logic,  on  the  other  hand, 
would  inquire  whether  the  idea  is  valid,  that  is,  whether  or 
not  it  is  true.3  We  should  thus  arrive  at  a definition  of  psy- 
chology such  as  that  of  Edmund  Husserl,  who  in  his  attempts 
to  determine  the  basis  of  pure  logic  emphasized  the  char- 
acter of  psychology  as  an  empirical  science  by  assigning  it 
the  task  of  investigating  descriptively  the  subjective  experi- 
ences or  contents  of  consciousness  according  to  their  funda- 
mental kinds  or  forms  of  complication,  and  of  determining 
genetically  the  manner  of  their  origin  and  decay,  the  causal 
forms  and  laws  of  their  formation  and  transformation.4  In 
his  own  analysis,  indeed,  a strongly  logistic  tendency  made 
itself  felt,  calling  forth  the  sharp  criticism  that  his  psy- 
chology merely  afforded  an  opportunity  for  the  application 
of  pure  logic.5 

1 [English  translation,  1895.  Trs.] 

2 Cf.,  e.  g.,  B.  A.  Riehl,  “Logik,”  in  Kultur  der  Gegenwart,  I,  6,  1908, 
p.  76.  On  the  modem  psychology  of  thought,  see  the  dissertation  of  E. 
Durr,  “Literaturbericht,”  pp.  1 ff.,  Arch.f.  d.  ges.  Psychologie,  VI,  1906. 

3 Praludien,  1884,  p.  23. 

iLogische  Untersuchungen,  II,  1901,  p.  336. 

6 Cf.  Wundt,  Kleine  Schriften,  I,  1910,  pp.  569  ff. 


158 


HISTORY  OF  PSYCHOLOGY 


This  complete  separation  of  these  subjective  experiences 
or  contents  of  consciousness  from  the  objects  at  which  they 
are  directed  is  the  result  of  a long  process  of  development. 
Originally  this  separation  between  mental  acts  and  their 
objects  was  not  made  at  all,  in  so  far  as  this  was  possible  in 
view  of  the  rest  of  experience.  For  a long  time,  accord- 
ingly, we  find  a reflex  influence  of  the  objects  of  mental 
activities  upon  the  alleged  structure  of  those  activities 
themselves.1  The  thought  processes  or  the  processes  of 
volition  were  not  regarded  as  constituent  parts  of  the  con- 
crete stream  of  mental  events,  but  rather  as  events  which 
were  to  be  measured  by  reference  to  a standard  or  norm  like 
truth  or  goodness.  We  have  an  illustration  of  this  in  the 
definition  of  D’Alembert  cited  above.2  On  the  other  hand, 
the  reverse  process  took  place  also;  the  object  of  mental 
activity  was  resolved  by  psychologism  into  the  activity 
itself.  The  logical  law  was  now  declared  to  be  a natural 
law  of  psychology,  and  the  conceptual  relation  expressed 
in  a thought  was  interpreted  as  merely  an  intellectual 
experience.  For  the  purely  logical  relation  expressed  by 
the  law  of  contradiction,  namely  that  contradictory  predi- 
cates cannot  belong  to  the  same  subject  at  the  same  time, 
psychologism  substituted  the  real  incompatibility  of  two 
mutually  contradictory  acts  of  judgment  as  empirical  mental 
processes  in  the  same  mind.  It  was  only  in  contrast  with 
these  various  forms  of  usurpation  that  the  view  of  mental 
states  as  independent  realities  emerged. 

Of  course,  efforts  were  hereby  not  excluded  to  maintain 
a connection  between  psychology  and  epistemological  prob- 
lems, a connection  which  would  seem  to  be  inevitable,  owing 
to  the  fact  that  all  processes  of  knowledge  are  presented  in 
individual  experience.  Paul  Natorp  declared  the  subject- 
matter  of  psychology  to  be  the  subjective  aspect  of  experi- 
1 Cf.,  p.  144.  2 Cf.  p.  149. 


PSYCHOLOGY  AS  A SCIENCE 


159 


ence,  prior  to  all  processes  of  objectification.  Now,  since 
the  fundamental  laws  of  objectification  and  the  laws  which 
immediately  complete  the  process  of  objectifying  the  phe- 
nomena are  different  from  each  other  in  the  same  sense  in 
which  the  a 'priori  constituents  of  consciousness  are  different 
from  the  empirical,  it  is  possible  to  distinguish  a purely 
a priori  part  of  psychology,  which  can  be  referred  to  phi- 
losophy as  a correlate  to  the  purely  objective  criticism  of 
knowledge.1  A still  closer  affiliation  of  psychology  with 
philosophy  is  found  in  H.  Cohen.  The  task  of  psychology 
within  the  general  field  of  philosophy  is  to  deal  with  the 
problem  of  the  unity  of  social  consciousness.  It  is  true, 
psychology  describes  consciousness  according  to  its  ele- 
ments; but  these  elements  are  necessarily  hypothetical,  since 
it  is  impossible  for  one  who  operates  with  consciousness  to 
lay  bare  that  with  which  consciousness  really  begins.2  This 
hypothetical  character  of  the  elements  of  consciousness,  to 
be  sure,  seems  to  conflict  with  the  characterization  of  mental 
elements  expressed  elsewhere;3  still,  it  must  be  remembered 
that  the  fundamental  conception  of  psychology  as  a philo- 
sophical science  which  is  in  question  here  is  distinctly  differ- 
ent from  the  conception  of  an  empirical  science,  which  also 
represents  the  result  of  the  effort  to  articulate  psychology 
with  natural  science. 

iff)  Psychology  and  Natural  Science:  Differentiation  of 
Physical  and  Psychical  Phenomena 

To  the  definition  of  psychology  bequeathed  by  metaphys- 
ics as  the  science  of  the  soul  has  been  opposed  the  definition 
of  it  as  the  science  of  mental  phenomena.4  The  latter  defi- 

1 Einleitung  in  die  Psychologie  nach  kritischer  Methode,  1888,  pp.  43, 124. 

2 Logik  der  reinen  Erkenntniss , 1902,  p.  16. 

3 Cf.  Chapter  VII,  3,  below. 

4 Cf.  F.  Brentano,  Psychologie  v.  emp.  Standpunkt,  I,  pp.  10  ff. 


160 


HISTORY  OF  PSYCHOLOGY 


nition  was  prompted  by  the  same  motive  as  prompted  critical 
reflection  to  discontinue  the  old  definition  of  physical  science 
as  the  science  of  bodies,  and  to  substitute  therefor  the  defi- 
nition of  it  as  the  science  of  physical  phenomena.  The  in- 
sight which  was  obtained  early  in  the  history  of  philosophy 
that  the  objects  of  what  is  called  external  perception  are 
only  phenomena  Locke  once  illustrated  by  a celebrated 
psychological  experiment.  Having  warmed  one  hand  and 
cooled  the  other,  he  plunged  both  into  the  same  vessel 
filled  with  water,  with  the  result  that  one  hand  perceived 
cold  while  the  other  perceived  warmth.  But  since  warmth 
and  cold  could  not  exist  simultaneously  in  the  same  water, 
he  regarded  the  phenomenal  nature  of  these  perceptions  as 
proved. 

In  the  application  of  this  concept  of  appearance  to  the 
realm  of  inner  perception,  which  came  much  later,  an  effort 
was  made  to  avoid  the  implication  that  mental  contents 
were  the  states  of  a substance.  This  is  illustrated  in  the 
definition  of  psychology  accepted  by  John  Stuart  Mill,1 
who  asserted  the  task  of  psychology  to  be  the  investigation 
of  the  course  of  mental  states,  which  was  controlled,  accord- 
ing to  him,  by  the  well-known  laws  of  association.2  In  con- 
nection with  complex  phenomena  the  question  arises  as  to 
whether  they  can  be  explained  as  the  joint  products  of  men- 
tal processes  or  whether  they  are  to  be  regarded  as  novel 
formations.  The  phenomenalistic  point  of  view,  however, 
disclaims  any  intention  of  limiting  the  task  of  psychology. 

The  definition  of  psychology  as  the  science  of  mental 
phenomena  has  been  represented  on  the  Continent  by  Franz 
Brentano.3  Brentano  is  particularly  interested  in  the  cri- 
teria according  to  which  mental  phenomena  can  be  unam- 
biguously distinguished  from  physical.  The  characteriza- 
tion of  mental  phenomena  as  distinguished  from  physical 

i Logic,  VI,  chap.  4,  § 3.  2 Cf.  p.  101,  above.  3 Op.  cit.,  101  ff. 


PSYCHOLOGY  AS  A SCIENCE 


161 


has  often  been  merely  negative.  Originally  the  distinguish- 
ing feature  was  spatial.  Physical  phenomena  had  extent, 
while  mental  phenomena,  thinking,  willing,  and  the  like, 
had  neither  extent  nor  any  other  spatial  characteristic. 
This  served  as  the  differentiating  mark  in  the  metaphysical 
systems  of  Descartes  and  Spinoza,  and  it  was  adopted  by 
Kant,  who  regarded  space  as  the  form  of  outer  sense.  Still 
more  recently  inner  experience  has  been  defined  negatively 
by  Bain  on  the  basis  of  the  absence  of  spatial  attributes.1 
The  objection  has  been  urged  against  this  criterion  that 
there  are  also  physical  phenomena  which  do  not  have  the 
attribute  of  extent.  Tones  and  odors  have  always  been 
denied  an  original  spatial  quality.  Berkeley  even  denied 
spatial  characteristics  to  color,  Plattner  to  taste  impressions, 
and  many  psychologists  from  Hartley  to  Herbart  and  Spen- 
cer have  not  admitted  that  space  is  an  original  attribute  of 
any  phenomenon  of  the  outer  sense.  Convinced  of  the 
inadequacy  of  these  negative  definitions,  Brentano  en- 
deavored to  find  some  positive  characteristics  of  mental 
phenomena  which  would  distinguish  them  unequivocally 
from  physical.  The  most  important  one  of  these  he  found 
to  be  the  “intentional”  character  of  psychical  phenomena: 
they  are  phenomena  which  intentionally  contain  an  object. 
A second  characteristic  given  by  Brentano  is  that  they  are 
discoverable  only  by  introspection,  thus  reverting  in  a pecu- 
liar way  to  the  old  doctrine  of  inner  sense.2 

In  addition  to  this  phenomenology  of  consciousness  rep- 
resented by  Brentano  and  his  school  there  is  observable  a 
second  main  tendency  which  determines  the  relation  between 
psychology  and  natural  science  by  the  point  of  view  from 
which  an  item  of  experience  is  to  be  regarded.  The  example 
of  natural  science  suggested  to  psychology  a treatment  of 
its  objects  in  analogy  with  the  treatment  of  natural  science. 

1 Mental  Science,  1868,  Intr.,  chap.  I.  2 Cf.  p.  84,  above. 


162 


HISTORY  OF  PSYCHOLOGY 


Thus  Rickert  maintained  that  psychology  must  transform 
the  manifold  of  psychical  experience  into  a conceptual  order, 
just  as  natural  science  substitutes  a conceptual  order  for 
the  manifold  of  sense  experience.1  This  demand  was  most 
completely  met  by  Miinsterberg.  For  Miinsterberg  the 
object  of  psychology,  like  the  object  of  natural  science,  is  a 
product  of  abstraction.  It  came  into  existence  logically 
through  the  fact  that  reality  was  objectified,  the  value 
objects  of  the  actual  ego  thus  detached  from  the  subject, 
and  actuality  transformed  into  experienceable  processes. 
Within  this  objectified  world  natural  science  and  psychology 
were  differentiated  in  such  a manner  that  the  latter  had  to 
do  only  with  objects  which  exist  solely  for  the  activity  of 
one  subject.2 

On  the  other  hand,  the  necessity  for  such  a conceptual 
translation  has  been  denied  on  the  ground  of  the  direct, 
immediate  reality  of  the  experience  to  be  thus  transmuted. 
This  position  has  been  taken  by  Wundt,  who  has  defined 
psychology  tersely  as  the  science  of  immediate  experience, 
thus  supplementing  natural  science,  which  is  the  science  of 
mediate  experience.  Faithfully  as  this  view  of  psychical 
facts  as  a sphere  of  reality  of  equal  validity  with  the  reality 
of  mediate  experience  champions  the  rights  of  psychology 
in  its  relation  to  natural  science,  nevertheless  the  epistemo- 
logical presuppositions  underlying  this  distinction,  in  conse- 
quence of  which  conscious  experience  and  objects  differ  only 
according  to  the  point  of  view  adopted,  have  often  been 
controverted,  particularly  by  the  representatives  of  act  psy- 
chology. 

In  recent  times  decided  doubt  has  been  cast  upon  all  these 
distinctions.  The  modern  opponents  of  metaphysics  have 
tried  to  drive  the  old  metaphysics  out  of  its  last  lurking-place. 

1 Grenzen  der  naturwissenschaftlichen  Begriffsbildung,  I,  pp.  183  ff. 

2 Grundziige  der  Psychologie,  1900,  p.  202. 


PSYCHOLOGY  AS  A SCIENCE 


163 


This  tendency  produced  the  empiriocriticism  of  Mach  and 
Avenarius,1  which  recognized  everything  which  we  immedi- 
ately feel  as  a complete  experience.  While  the  customary 
distinctions  between  physical  and  psychical  lead  to  manifold 
ambiguities,  the  new  definition  of  the  psychical  asserts  the 
object  of  psychology  to  be  that  aspect  of  a complete  experi- 
ence of  an  individual  which  is  dependent  upon  the  individual 
for  its  existence.  Instead  of  the  older  opposition  of  nature 
and  spirit  bequeathed  by  naturalistic  modes  of  thought,  we 
now  have  as  the  constituents  of  our  psychical  life  psychical 
experiences,  determinate  sensations  of  color,  tones,  and  so 
forth,  which  stand  on  precisely  the  same  footing  as  the  con- 
tents of  inner  experience.2  In  the  terminology  created  by 
Avenarius,  which  substituted  for  the  individual  the  nervous 
part  system  C,  this  definition  tends  to  assume  a materialistic 
hue,  from  which,  however,  it  later  freed  itself  by  the  suppres- 
sion of  the  insidious  system  C. 

The  enticing  doctrines  of  empiriocriticism  have  occa- 
sionally been  responsible  for  an  unhistorical  polemic  against 
psychology  like  that  of  R.  Willy,  for  example,  who  has  ex- 
pressed the  opinion  that  psychology  is  at  the  present  time 
undergoing  a crisis,  and  has  sought  to  show  that  the  systems 
of  Wundt,  Rehmke,  and  Brentano  really  rest  upon  a meta- 
physical spiritualism.3  The  point  of  his  criticism  is  that  the 
attempts  to  assign  psychology  a special  subject-matter,  like 
Rehmke’s  psychical  concrete  or  Brentano’s  psychical  phe- 
nomena, do  not,  in  spite  of  their  pretence  at  pure  empiricism, 
escape  spiritualistic  metaphysics.  But  psychology,  which 
has  so  often  been  the  target  of  epistemological  attacks  of  this 
sort,  will  survive  this  criticism  also,  deeds  being  more  con- 
vincing than  words. 

1 Vierteljahrsschrift  f.  wiss.  Phil.,  XVIII,  1894,  137,  400;  XIX,  1895, 
pp.  1,  129. 

2 Cf.,  e.  g.,  H.  Cornelius,  Eirileitung  in  die  Philosophic,  1903,  pp.  177  ff- 

3 Vierteljahrsschrift  f.  wiss.  Phil.,  XXI,  1897,  pp.  79,  227,  332. 


164 


HISTORY  OF  PSYCHOLOGY 


One  question  as  to  the  future.  If  psychology,  according 
to  the  modern  conception  developed  here,  is  to  bear  the  same 
fundamental  relation  to  the  mental  sciences  as  physics  bears 
to  the  natural  sciences,  there  must  exist  in  connection  with 
psychology  a certain  border  realm  similar  to  the  philosophy 
of  nature  affiliated  with  natural  science.  It  might  be  con- 
tended that  the  history  of  metaphysics,  in  which  philosoph- 
ical points  of  view  have  dominated,  shows  plainly  enough 
how  wddely  the  latter  are  relinquished  by  the  modes  of 
thought  of  a truly  empirical  psychology.  Still,  there  is  a 
second  way  in  which  the  phenomena  of  consciousness  can 
be  considered,  a way  which  has  its  counterpart  in  the  inves- 
tigation of  the  presuppositions  of  the  exact  sciences.  As  one 
investigates  here  the  basis  of  hypothetical  constructions  and 
the  significance  of  axiomatic  assumptions,  so  it  is  possible 
to  raise  the  question  in  psychology  as  to  the  nature  of  the 
fundamental  hypotheses  employed,  and  whether  there  are 
also  in  this  field  propositions  of  axiomatic  significance.  The 
history  of  epistemology  and  of  ethics  illustrates  the  abun- 
dant attempts  to  discover  primitive  relations  among  con- 
tents of  consciousness  which  exhibit  axiomatic  character. 
These  have  always  been  measured  by  a logical  or  ethical 
norm.  Thus  it  was  taught,  for  example,  that  there  existed 
a necessary  connection  between  the  true  knowledge  of  a 
moral  good  and  the  act  of  will  directed  to  the  production  of 
this  good.  For  concrete  volitional  experiences,  however,  no 
such  axiomatic  principle  obtained.  A few  such  propositions 
which  have  a principial  significance  for  empirical  psychology 
have  indeed  been  exploited,1  and  we  shall  come  upon  them 
again  in  the  discussion  of  the  special  fundamental  concepts 
of  psychology.  Nevertheless,  the  problem  itself  belongs  to 
the  future.  It  is  possible  that  reflection  upon  the  hypothet- 
ical principles  underlying  psychology  will  open  to  us  vistas 
1 Cf.  p.  142,  above. 


PSYCHOLOGY  AS  A SCIENCE 


165 


as  far-reaching  as  the  theory  of  relativity,  for  example,  in 
modern  physics.1 

1 [For  the  latest  conceptions  of  psychology  as  discussed  at  present, 
particularly  among  American  psychologists,  cf.  esp.  Angell,  “Behavior 
as  a Category  of  Consciousness,”  Psych.  Rev.,  1913,  pp.  255-270,  and 
Watson,  “Psychology  as  the  Behaviorist  Views  It,”  Psych  Rev.,  1913, 
pp.  158-177.  Trs.] 


CHAPTER  VI 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY:  CONSCIOUSNESS 

Considering  how  far  back  reflection  on  psychological 
questions  extends,  the  real  subject-matter  of  psychology  was 
late  in  receiving  conceptual  formulation.  As  qualities  or 
functions  of  a metaphysically  defined  soul,  psychical  con- 
tents were  mere  manifestations,  much  in  the  same  way  that 
natural  processes  were  the  manifestations  of  physical  bodies 
which  acted  as  their  bearers.  It  was  only  when  psychical 
contents  were  viewed  in  their  immediate  reality  as  parts  of 
a unified  field  of  experience  that  psychology  acquired  a defi- 
nite subject-matter.  The  development  of  the  concepts  of 
consciousness  merely  means,  therefore,  the  gradual  appre- 
hension of  psychical  contents  in  their  immediate  reality  as 
conscious  experiences.  The  question  whether  the  concept 
of  consciousness  is  wide  enough  to  include  the  entire  range 
of  psychical  events  has  given  rise  to  controversies  concern- 
ing the  limits  of  consciousness,  which  have  centred  princi- 
pally about  the  question  of  the  significance  of  the  uncon- 
scious in  psychology.  Another  and  different  problem  was 
that  of  the  range  of  consciousness,  which  led  to  the  consid- 
eration of  the  graduation  of  conscious  contents  according 
to  degrees  of  clearness.  The  latter  connected  itself  mainly 
with  the  accentuation  of  special  conscious  contents  in  the 
experience  of  attention. 

i.  The  History  of  the  Concept  of  Consciousness 

(a)  Early  Developments  of  the  Concept 

The  problem  of  consciousness  can  hardly  be  said  to  have 
existed  for  the  philosophy  of  antiquity.  It  is  true  that 

166 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  167 


Plato  points  to  the  necessity  of  reflection  (cfrpovrjo-is)  and  of 
self-knowledge,  but  the  notion  of  self-knowledge  is  much 
too  narrow  to  serve  the  purpose  of  defining  the  boundaries 
of  the  subject-matter  of  psychology.  The  consciousness  to 
which  Plato  refers  is  the  consciousness  of  what  our  experi- 
ence objectively  signifies.  Here,  too,  we  see  how  the  object 
at  which  psychical  activities  are  directed  becomes  normative 
for  those  activities  themselves.1 

The  limitation  of  ancient  psychology  referred  to  reveals 
itself  with  particular  clearness  in  Aristotle’s  attempt  to 
determine  the  boundaries  of  the  psychical.  Psychology, 
according  to  Aristotle,  has  to  do  with  the  phenomena  of  life 
in  plant,  animal,  and  man.  But  wTe  find  no  criterion  by 
which  we  are  to  distinguish  psychical  phenomena  from  vital 
processes  in  general.  Even  in  the  consideration  of  specific 
psychical  contents  there  is  no  attempt  to  point  out  any 
common  characteristic  which  belongs  to  them  as  contents 
of  consciousness.  Neither  the  arrangement  in  a hierarchy 
of  lower  and  higher  functions,  in  which  the  conscious  func- 
tions are  naturally  classed  together,  nor  the  distinction 
between  the  perception  of  a sense-impression  and  the  per- 
ception of  this  perception  itself,  between  the  thought  of  an 
object  and  the  thought  of  the  thought,2  yields  any  formula 
which  comprehends  the  whole  of  consciousness  as  such. 
Suggestions  of  the  concept  of  consciousness  are  found  in 
Aristotle  only  in  connection  with  the  metaphysical  treat- 
ment of  the  fact  of  self-consciousness,  as  in  that  memorable 
passage  in  the  Metaphysics  which  describes  the  nature  of 
God.3  God  alone,  who  is  pure  activity  ( actus  purus),  thinks 
himself,  his  thought  being  his  sole  object. 

The  characteristic  thought  of,  in  the  first  instance,  merely 
as  self-consciousness  was  destined  to  expand  into  the  general 
concept  of  consciousness.  This  step,  as  has  been  shown, 

1 Cf.  pp.  144  /.,  above.  2 Cf.  p.  72,  above.  3 XII,  8,  9. 


168 


HISTORY  OF  PSYCHOLOGY 


was  not  taken  until  Neo-Platonism.1  The  Neo-Platonic 
interpretations  of  the  concept  of  consciousness  were  partly 
based  upon  the  thesis  that  that  which  cannot  know  itself 
cannot  know  anything  else.  According  to  Plotinus,  the  soul 
comes  to  self-consciousness  through  its  vision  of  the  Nous. 
The  result  of  this  act  is  an  identity  of  the  vow,  vorja^ 
and  vorjTov.  This  is  a description  of  the  experience  of  self- 
consciousness  which  is  at  once  mystical  and  sensuous.  More 
important,  however,  is  the  fact  that  Plotinus  ascribed  to  the 
Nous,  which  he  defined  as  a manifold  containing  within  itself 
the  principle  of  unity,2  the  attribute  of  self-consciousness 
(crvvaLcrdricus  ainrjs),  and  thus  gave  general  currency  to  an 
expression  which  had  occurred  only  occasionally  in  writers 
like  Alexander  of  Aphrodisias  and  Galen.  From  now  on  the 
definite  separation  between  consciousness  and  the  uncon- 
scious possession  of  an  idea  becomes  customary  among  the 
Neo-Platonists.  To  the  activities  of  sensation,  presenta- 
tion, etc.,  is  superadded  an  accompanying  consciousness 
(irapaKoXovdrjcns)  which  is  further  described  as  an  activity 
of  reflection  ( avcuca/JLTrTovcrrp ? t Siavoia<;). 

While,  therefore,  the  distinctive  character  of  conscious- 
ness as  such  remains  unrecognized,  the  problem  of  con- 
sciousness emerges  more  distinctly  than  before.  The  em- 
phasis upon  the  inner  man  in  the  teachings  of  Christianity 
was  also  bound  to  assist  the  process  of  psychological  self- 
reflection. In  Augustine  the  knowledge  by  the  soul  of  itself 
is  one  of  its  most  assured  possessions.  Even  if  we  should 
doubt  the  existence  of  the  outer  world,  this  very  doubt 
would  assure  us  of  our  own  psychical  existence.  The  fact 
that  Augustine  found  an  epistemological  basis  in  the  imme- 
diate deliverance  of  self-consciousness,  an  insight  of  great 
moment  to  the  future  of  philosophy,  shows  how  vitally  he 
grasped  the  fundamental  psychological  principle  involved. 

1 Siebeck,  op.  cit.,  I,  2,  pp.  337  ff.  2Enn.,  V,  9,  6. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  169 


For  a thousand  years,  however,  this  thought  remained  un- 
developed. It  became  merged  with  the  doctrine  of  the 
inner  sense,  as  in  Thomas  Aquinas,  for  example,  who,  not- 
withstanding his  theory  of  inner  perception,1  gave  the  col- 
orless description  of  self-consciousness  as  an  act  of  knowl- 
edge in  which  spiritual  substances  return  upon  themselves. 

( b ) Development  of  the  Modern  Concept  of  Consciousness 

The  discovery  of  consciousness  as  a fundamental  psychi- 
cal fact  was  not  made  before  Descartes.  It  is  true  that 
Descartes  was  influenced  in  many  of  his  psychological  views 
by  that  bold  empiricist  Vives.2  Nevertheless,  his  distinction 
between  extended  and  thinking  substance  was  tantamount 
to  the  designation  of  the  field  of  psychical  phenomena  or 
contents  of  consciousness  as  a permanent  subject-matter  of 
psychology.  It  has  been  asserted  that  psychology,  in  so 
far  as  it  was  not  metaphysical,  had  not  made  any  impor- 
tant advance  over  Aristotle  up  to  the  time  of  Descartes. 
It  is  certain,  in  any  case,  that  the  discovery  of  Descartes 
introduced  a characteristic  difference  between  modern  psy- 
chology and  the  psychology  of  Aristotle.  Descartes  clearly 
enunciated  the  truth  that  the  appearance  of  a psychical  con- 
tent was  identical  with  the  consciousness  of  the  same.3 
This  has  remained  the  point  of  departure  for  empirical  psy- 
chology; it  was  already  self-evident  for  Locke  that  to  have 
ideas  and  to  be  conscious  of  them  was  one  and  the  same 
thing.4 

In  keeping  with  its  origin  in  epistemological  considera- 
tions, the  Cartesian  concept  of  consciousness  has  partly 

1 See  p.  74,  above. 

2 This  has  been  emphasized  particularly  by  Hoffding,  Geschichte  d. 
n.  Phil.,  I,  p.  259. 

3 Princ.  Phil.,  I,  9. 

i Essay  on  the  Human  Understanding,  bk.  II,  chap.  I,  § 9. 


170 


HISTORY  OF  PSYCHOLOGY 


been  refined  in  modern  psychology  in  an  epistemological 
direction,  and  it  has  partly  been  freed  from  the  strictly  intel- 
lectualistic  character  given  to  it  by  Descartes,  according  to 
whom  all  conscious  contents  consist  in  cognitive  processes. 
It  was  not  until  these  modifications  occurred  that  the  con- 
cept was  wide  enough  to  include  equally  all  psychical 
phenomena. 

The  first  of  these  developments  led  to  considerable  dif- 
ferences in  point  of  view  in  the  treatment  of  self-conscious- 
ness. The  empirical  point  of  view  which  sought  to  resolve 
the  fact  of  self-consciousness  or  the  ego  into  empirically 
given  contents  of  consciousness  was  never  more  brilliantly 
represented  than  by  David  Hume.  The  upshot  of  his  criti- 
cism was  the  total  rejection  of  the  idea  of  soul  substance,  on 
the  ground  that  such  a substance  always  presupposed  the 
spatial  connection  of  the  contents  of  consciousness  with 
something  extended  or  inextended.  Just  as  little  are  we  able 
to  discover  in  personal  identity  or  the  ego  the  principle  of 
unity  within  consciousness,  as  philosophers  have  claimed. 
“Our  notions  of  personal  identity  proceed  entirely  from  the 
smooth  and  uninterrupted  progress  of  the  thought  along  a 
train  of  connected  ideas.”1 

The  opposite  tendency  reached  its  climax  in  post-Ivantian 
philosophy.  Kant’s  much  admired  doctrine  of  the  unity  of 
transcendental  apperception  found  in  self-consciousness  that 
relation  between  the  contents  of  consciousness  and  a self 
which  Fichte  erected  into  a philosophical  principle.  Ever 
since  the  Neo-Platonists  compared  this  inexpressible  rela- 
tion between  the  ego  and  the  contents  of  consciousness  with 
the  relation  between  the  centre  of  the  circle  and  the  circle 
itself,  many  thinkers  have  sought  to  give  an  answer  to  this 
riddle  which  continues  to  stand  at  the  threshold  of  psy- 
chology. They  were  all  surpassed  by  Fichte,  however,  when 
1 Hume,  Treatise  of  Human  Nature,  bk.  I,  part  IV,  § VI. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  171 


he  undertook  to  evoke  the  whole  universe  from  the  bare  fact 
of  this  relation  to  the  ego.  The  glorification  of  the  fact  of 
self-consciousness  which  his  constructions  implied  aroused 
the  protests  of  more  cautious  psychologists.  Fichte’s  doc- 
trine of  self-consciousness  may  be  summed  up  in  the  follow- 
ing formula : The  ego  is  that  which  thinks  itself.  Herbart 
proved  the  imsoundness  of  this  formula  by  showing  that  it 
involves  an  infinite  regress.  The  “itself”  can,  in  turn,  be 
nothing  else  than  the  self,  so  that  the  Fichtean  proposi- 
tion is  equivalent  to  the  proposition:  the  ego  is  that  wdtich 
thinks  itself,  etc.,  ad  infinitum. 

Of  greater  significance  for  psychology  was  the  extension 
of  the  concept  of  consciousness  to  include  all  psychical 
phenomena  already  suggested  in  Leibniz’s  important  doc- 
trine of  the  grades  of  consciousness,  in  virtue  of  which  all 
conscious  states  pass  into  each  other  by  continuous  trans- 
itions. To  express  this  unique  character  of  consciousness 
Leibniz  employed  a terminology  partly  invented  by  him- 
self. He  used  the  old  word  perceptio,  in  the  first  place, 
to  indicate  the  unconscious,  passive  state  of  the  monad, 
in  which  it  represents  only  the  external  world.  Opposed 
to  this  is  the  conscious  state,  designated  by  the  newly 
coined  word  apperceptio,  which  is  that  activity  of  the 
monad  through  which  it  becomes  aware  of  its  own  percep- 
tions. The  word  consciousness,  meanwhile,  passed  into  phil- 
osophical usage  as  a translation  of  conscientia.  This  has, 
in  spite  of  many  shifts  of  meaning,  retained  the  ethical 
significance  of  conscience,  illustrating  how  the  concept  of 
consciousness  is  foreshadowed  in  the  terminology  of  ethico- 
religious  reflection.  It  is  true  that  the  Stoics  already  used 
the  philosophical  terms  avveiSrjcns  (consciousness)  and  avv- 
aiadr)cn<;  erven aaecos  (self-consciousness),  with  which  Sen- 
eca first  associated  the  term  conscientia.  In  conscientia, 
however,  the  ethico-religious  significance  of  conscience  re- 


172 


HISTORY  OF  PSYCHOLOGY 


mained  predominant,  for  which  the  much-disputed  term 
synteresis  was  used  in  the  Middle  Ages.  The  etymology 
of  this  word,  as  we  learn  from  Albert  von  Bollstadt,  was 
already  in  dispute  in  Scholastic  philosophy.  Attention  has 
recently  been  called  to  the  fact  that  r rjprjcns  was  used  by 
certain  physicians  of  the  latter  half  of  the  Middle  Ages  as 
the  terminus  technicus  for  observation.  According  to  the 
use  of  aw  a icr  9 ye  is  or  cri weiSyais  by  Stoicism,  and  still 
more  by  Neo-Platonism,  awrypycns  would  thus,  in  the 
first  instance,  have  meant  self-observation.  If  the  deriva- 
tion suggested  here  is  correct,  the  history  of  this  concept 
offers  an  instructive  example  of  the  fact  that  a term  of 
purely  psychological  import  which  had  been  restricted  to 
an  ethico-religious  signification  had  its  original  meaning 
restored  only  by  the  roundabout  way  of  translation. 

2.  The  Concept  of  the  Unconscious 

(a)  Representatives  and  Opponents  of  the  Notion  of  the 
Unconscious 

The  concept  of  consciousness  in  Leibniz  was  so  compre- 
hensive as  to  include  the  notion  of  the  unconscious  as  well. 
The  idea  of  petites  perceptions  gave  rise  to  the  idea  of  a 
monad  filled  at  each  moment  with  an  infinite  number  of 
perceptions.  Since  any  number  of  intermediate  stages  may 
exist  between  a given  grade  of  consciousness  and  the  state 
of  unconsciousness,  the  petites  perceptions  need  to  be  only 
relatively  unconscious.  Leibniz  gives  a number  of  reasons 
why  the  petites  perceptions  do  not  possess  the  degree  of 
consciousness  of  ordinary  conscious  contents.  They  are 
either  too  weak  to  rise  to  consciousness  or  they  occur  in 
such  large  numbers  as  to  makU.The  consciousness  of  the 
separate  ones  impossible.  Finally,  they  may  be  crowded 
out  by  other  particularly  strong  contents  of  consciousness. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  173 


It  is  possible  that  Leibniz  is  here  influenced  by  the  older 
view  of  Malebranche,1  who  had  deduced  the  original  uncon- 
sciousness of  so  many  ideas  from  the  impossibility  of  their 
simultaneous  apperception.  These  are  reflections  which 
anticipate  later  views  in  a remarkable  way  and  which 
illuminate  strikingly  the  significance  of  this  concept  of 
degrees  of  consciousness  for  the  subsequent  efforts  of  psy- 
chical mechanics. 

But  with  the  sharp  separation  of  perceptio  and  apper- 
ceptio  and  the  recognition  of  perceptiones  insensibiles 
Leibniz  approaches  the  conception  of  the  unconscious, 
while  he  abandons  completely  the  idea  of  a hierarchical 
arrangement  of  conscious  contents  on  the  basis  of  degrees 
of  clearness,  assuming  the  existence  of  innate  and,  in  the 
strict  sense,  unconscious  mental  contents.  In  the  polemic 
with  Locke,  who  takes  his  stand  on  the  ground  of  psy- 
chological experience,  the  rationalism  of  Leibniz  gains  the 
upper  hand.  In  the  criticism  of  Locke’s  theory  of  knowl- 
edge Leibniz  maintains  the  existence  of  innate  and  uncon- 
scious contents  said  to  contain  the  principles  of  theoretical 
and  practical  reason.  The  notion  of  these  unconscious  con- 
tents approaches  to  some  extent  that  of  psychical  disposi- 
tion, and  Leibniz,  indeed,  sought  to  render  their  existence 
vivid  by  comparing  them  with  memory  contents.2 

Leibniz’s  doctrine  of  unconscious  psychical  contents  read- 
ily passed  over  into  a number  of  very  diverse  psychologi- 
cal tendencies,  he  himself  having  thrown  out  suggestions 
for  various  applications  of  the  idea.  It  was  introduced 
into  association  psychology  by  the  elder  Mill,  who  spoke 
of  sensations  which,  on  account  of  habitual  inattention, 
do  not  rise  to  the  level  of  consciousness  at  all.  Hamilton 
pointed  to  unconscious  intermediate  links  which  we  are 

1 Rech.,  Ill,  27,  and  VI,  1,  5. 

8 Philosophische  Werke,  ed.  Gerhard,  V,  p.  75. 


174 


HISTORY  OF  PSYCHOLOGY 


obliged  to  assume  in  order  to  make  the  connection  of  our 
ideas  intelligible,  and  Lewes  went  still  further  with  the 
claim  that  the  great  majority  of  conscious  processes  ran 
their  course  unconsciously.  In  Maudsley,  finally,  uncon- 
scious psychical  activity  became  a fact  so  incontroverti- 
ble as  even  to  demand  the  physiological  treatment  of  psy- 
chology. 

The  concept  of  the  unconscious  is  developed  in  a different 
direction  by  Herbart.  According  to  Herbart,  those  ideas  are 
unconscious  which  lie  below  the  threshold.  True,  they  do 
not  represent  actual  presentation,  which  can  take  place 
only  above  the  threshold,  but  only  a tendency  to  presenta- 
tion. At  the  same  time  they  act  upon  one  another  accord- 
ing to  the  same  laws  which  govern  actual  presentations. 
As  an  auxiliary  conception  which  was  meant  to  explain 
conceptual  processes,  the  idea  of  unconscious  inference  came 
to  play  a part  in  the  later  spatial  theories  of  Helmholtz 
and  Zollner.  The  many-sided  utility  of  the  concept  of 
the  unconscious  shows  itself,  finally,  in  the  fact  that  it  was 
invoked  to  extricate  the  ego  doctrine  of  Fichte  from  the 
difficulties  in  which  it  had  become  involved  in  connection 
with  the  problem  of  self-consciousness.  Schelling  in  this 
way  arrived  at  a purely  speculative  deduction  of  the  uncon- 
scious.1 The  production  of  the  world  can  never  be  com- 
prehended by  beginning  with  an  ego  already  conscious  of 
itself.  But  the  ego  which  has  become  conscious  of  itself 
can  look  back  upon  a moment  of  its  own  activity  in  which 
it  was  not  as  yet  conscious  of  itself,  and  thus  the  beginning 
of  the  ego’s  activity  retreats  into  the  realm  of  the  uncon- 
scious. With  all  his  appeal  to  the  facts  of  psychological 
experience,  large  concessions  were  later  made  to  the  notion 
of  the  unconscious  by  Hartmann  in  his  Philosophy  of  the 
Unconscious. 


1Werke,  Abt.  I,  vol.  Ill,  pp.  348/. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  175 

Over  against  this  large  number  of  champions  of  the  doc- 
trine of  the  unconscious  we  find  a second  group  of  think- 
ers, no  less  influential  than  the  former,  who  oppose  the  doc- 
trine. It  was  rejected  by  the  leading  English  psychologists, 
J.  S.  Mill,  Bain,  and  Spencer,  and  by  H.  Lotze  in  Germany. 
Ulrici  also  denied  the  existence  of  unconscious  psychical 
activity,  although  his  own  concept  of  consciousness,  of 
course,  differs  from  the  usual  one.1  Fechner’s  fundamental 
psychological  law,  indeed,  led  him  to  a point  beyond  which 
a conscious  correlate  of  psychophysical  activities  disappears. 
Nevertheless,  he  evaded  the  assumption  of  unconscious 
sensations  and  ideas  by  holding  that  only  the  psycho- 
physical activities  persisted.2  Wundt,  who  in  his  earlier 
psychological  writings3  still  admitted  unconscious  inference, 
which  seemed  to  be  so  important  for  the  theory  of  percep- 
tion, later  took  stand  against  the  assumption  of  uncon- 
scious psychical  activity.  In  order  to  satisfy  the  demands 
of  explanatory  psychology  Lipps,  indeed,  fell  back  upon 
unconscious  psychical  processes.  The  appearance  of  these 
processes,  however,  are,  even  in  Lipps,  always  accompanied 
by  consciousness. 

(b)  Arguments  for  and  against  the  Unconscious 

The  various  lines  of  thought  in  the  controversy  over  the 
unconscious  can  be  best  followed  if  presented  in  the  form 
of  the  arguments  for  and  against  the  unconscious  which 
were  put  forward  by  the  participants  in  the  discussion  of 
the  question.4  As  is  the  case  in  so  many  fundamental  con- 
cepts of  psychology,  the  demand  made  was  partly  one  of 

1 Cf.  p.  80.  2 Elemente  der  Psychophysik,  II,  1860,  p.  438. 

3 Beitr&ge  zur  Theorie  der  Sinneswahrnehmung , 1862.  See  also  his 
Lectures  on  Human  and  Animal  Psychology , 1863. 

4 Cf.  F.  Brentano,  Psych,  v.  emp.  Slandpunkte,  1874,  pp.  137  ff., 
which  the  present  discussion  partly  follows. 


176 


HISTORY  OF  PSYCHOLOGY 


explanation,  partly  one  of  description.  The  arguments  ac- 
cordingly fell  into  two  classes,  in  the  first  of  which  the 
unconscious  is  invoked  in  the  service  of  causal  explanation, 
and  in  the  second  of  which  difficulties  are  pointed  out  in  the 
pure  phenomenology  of  consciousness  which  cannot,  it  is 
held,  be  solved  without  having  recourse  to  the  hypothesis 
of  unconscious  psychical  phenomena.  The  difficulties  raised 
by  the  demand  for  causal  explanations  were  obviously 
greater  than  those  presented  by  the  task  of  pure  description. 
An  unconscious  psychical  process  was  accordingly  invoked 
either  as  the  cause  of  an  empirical  conscious  process,  or  else 
the  attempt  was  made  to  prove  the  existence  of  uncon- 
scious psychical  processes  on  the  basis  of  an  inverted  causal 
relationship. 

The  former  and  more  natural  use  of  the  unconscious  is 
the  one  most  frequently  found.  Thus  Sir  William  Hamil- 
ton argued  for  the  existence  of  unconscious  ideation  from 
the  occasional  absence  of  a series  of  intermediate  terms  in 
the  revival  of  a previous  train  oLassociation.1  However,  no 
one  who  agreed  with  Hamilton  in  his  assumption  has  been 
able  to  show  that  this  explanation  is  the  only  possible  one. 
The  same  applies  to  F.  A.  Lange,  who  explained  the  phe- 
nomenon of  the  blind-spot  by  supposing  that  the  eye  un- 
consciously infers  the  color  which  it  should  actually  see. 
The  theories  of  space  of  Helmholtz  and  Zollner  operated 
with  the  notion  of  unconscious  inference,  without  utilizing 
the  auxiliary  aids  employed  by  the  psychology  of  the  time 
in  order  to  do  justice  to  the  facts  without  invoking  uncon- 
scious intermediate  links.  Maudsley  and  Lewes  sought  to 
show  by  the  phenomena  of  reproduction  that  experiences 
which  rose  to  consciousness  in  dreams  or  in  recollection 
may  originally  have  existed  as  unconscious  psychical  phe- 
nomena. All  these  arguments  finally  combine  in  Hart- 
1 Lectures  on  Metaphysics  and  Logic,  I,  Lecture  XVIII. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  177 


mann,  who,  indeed,  goes  beyond  immediate  experience  in 
so  far  as  he  regards  conscious  and  unconscious  phenomena 
as  heterogeneous,  the  hypothesis  of  the  unconscious  thus 
losing  much  of  its  significance  for  empirical  psychology. 
Unconscious  psychical  phenomena  do  not  conform  to  the 
laws  of  experience  but  dissolve  into  an  eternally  uncon- 
scious and  unique  reality  possessing  wholly  transcendental 
attributes.1 

The  second  line  of  speculation  which  views  unconscious 
psychical  acts  as  the  effects  of  conscious  psychical  acts  is 
encountered  less  frequently.  A consideration  of  this  sort 
goes  back  to  Leibniz.  An  ocean  wave  produces  the  roar  of 
the  breakers,  but  if  it  is  only  a drop  of  water  which  falls 
we  hear  nothing  whatever.  But  we  must  have  an  audi- 
tory sensation  even  in  the  latter  case,  for  the  noise  of  the 
wave  consists  of  the  simultaneous  noises  of  the  single  drops 
which  compose  it.  An  analogous  idea  is  utilized  by  Ulrici 
for  visual  sensations.  Although  very  small  objects  are  not 
perceptible,  they  nevertheless  yield  some  visual  impression. 
For  larger  objects  are  perceptible  only  because  the  visual 
perception  is  the  result,  as  it  were,  of  a number  of  sense- 
impressions  which  separately  are  so  weak  as  to  escape  at- 
tention.2 This  conclusion  has  been  contradicted  by  the 
pretty  generally  recognized  principle  of  modern  psychology 
that  the  sum  of  effects  is  not  merely  quantitatively  different 
from  the  separate  members  or  components,  but  qualitatively 
as  well.  The  fact  that  the  after-image  shows  details  which 
were  not  observed  in  the  original  image  was  also  cited  by 
Ulrici  in  support  of  the  assumption  of  unconscious  sensa- 
tions.3 Helmholtz,  too,  has  given  a circumstantial  account 
of  similar  phenomena.4  Still,  it  has  never  been  proved  that 

1 Philosophie  des  Unbewussten,  2d  ed.,  pp.  473  jf. 

2 Gott  und  Mensch,  p.  294. 

3 Op.  cit.,  pp.  285  and  304.  4 Phys.  Optik,  p.  337. 


178 


HISTORY  OF  PSYCHOLOGY 


the  sensation  in  question  was  actually  unconscious,  and  the 
newer  analysis  of  the  processes  of  attention  has  suggested 
less  hypothetical  explanations  of  the  phenomenon  con- 
cerned than  the  one  here  employed. 

More  convincing  than  the  lines  of  reflection  just  enumer- 
ated was  the  assumption  that  the  strength  of  the  conscious- 
ness accompanying  a given  psychical  activity  stands  in  a 
functional  relation  to  the  strength  of  the  latter.  With 
sufficient  diminution  of  the  degree  of  strength  of  the  psychical 
phenomenon,  consciousness  could  disappear  entirely.  It 
was  on  the  basis  of  such  considerations  that  Beneke  ad- 
mitted the  existence  of  unconscious  psychical  activities.1 
The  doctrine  did  not  make  much  headway,  however,  as  the 
notion  of  psychical  measurement,  which  the  idea  of  the 
strength  of  psychical  activity  suggested,  tended  in  Fechner 
to  ignore  unconscious  sensations  and  to  put  in  their  place 
the  vague  notion  of  psychical  disposition.  Brentano, 
moreover,  broke  the  force  of  the  argument  for  the  uncon- 
scious by  considerations  of  a purely  psychological  character.2 
The  intensity  of  presentation  is  always  equal  to  the  intensity 
with  which  the  presented  content  appears.  The  intensity, 
therefore,  of  the  presentation  of  a presentation  must  be 
equal  to  the  intensity  with  which  this  presentation  itself 
appears.  In  virtue  of  the  veridical  character  of  inner  per- 
ception, the  apparent  intensity  of  conscious  presentations 
and  their  actual  intensity  coincide.  We  thus  arrive  at  the 
conclusion  that  in  the  case  of  any  conscious  presentation 
the  strength  of  the  presentations  referring  to  it  is  equal 
to  its  own  strength.  This  line  of  reflection  is  really  less 
significant  as  a refutation  of  Beneke  than  as  a characteristic 
of  Brentano’s  psychology.  A conclusion  which  at  the  out- 
set is  not  by  any  means  self-evident  will  follow  necessarily 
from  presuppositions  every  one  of  which  must  be  admitted 

1 Lehrb.  d.  Psych.,  2d  ed.,  § 57.  2 Op.  tit.,  p.  157. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  179 


if  one  accepts  as  one’s  point  of  departure  the  conception  of 
Brentano’s  psychology  as  the  doctrine  of  psychical  phe- 
nomena given  in  inner  perception. 

The  other  principal  line  of  evidence  for  unconscious 
psychical  activities  depending  upon  the  presuppositions  re- 
quired in  a purely  descriptive  account  of  conscious  phe- 
nomena made  capital  of  the  enormous  complication  which 
the  assumption  that  any  psychical  activity  was  a conscious 
activity  was  said  to  necessitate.  If  an  unconscious  psychical 
phenomenon  is  an  impossibility  we  should  have  to  assume, 
in  addition  to  the  presentation  of  a tone,  the  presentation 
of  this  presentation.  The  second  presentation,  in  turn, 
if  it  is  to  be  conscious,  requires  another  presentation  of  it- 
self, and  so  on,  the  simple  act  of  audition  thus  forcing  upon 
us  the  assumption  of  an  infinite  number  of  such  psychical 
activities.  Reflections  of  this  sort  arose  particularly  in 
connection  with  the  doctrine  of  the  inner  sense.  This  dif- 
ficulty connected  with  the  doctrine  of  the  inner  sense  had 
already  been  pointed  out  by  Aristotle  in  the  De  Anima. 
The  first  writer  to  deduce  from  this  difficulty  the  existence 
of  unconscious  psychical  activities  was  Thomas  Aquinas.1 
In  modern  times  Herbart  referred  to  the  fact  that  among 
the  various  masses  of  ideas,  each  of  which  apperceived  the 
preceding  one,  one  must  hold  the  ultimate  or  highest  place, 
and  that  it  cannot  itself  be  apperceived.2  For  Herbart, 
of  course,  the  existence  of  unconscious  ideas  was  already 
assured  on  other  grounds.  Although  the  difficulty  of  in- 
definite complication  of  mental  states  has  often  been  dis- 
cussed, it  has  seldom  supplied  a real  argument  for  the  ex- 
istence of  unconscious  psychical  phenomena.  Attempts 
have  sometimes  been  made  to  solve  this  problem  without 
resorting  to  the  assumption  of  unconscious  psychical  phe- 

1 See  p.  74. 

2 Psychologit  als  Wissenschaft,  Teil  II,  Absch.  II,  Kap.  5,  § 199. 


180 


HISTORY  OF  PSYCHOLOGY 


nomena  by  asserting  that  the  psychical  activity  and  the 
objects  toward  which  it  is  directed  are  one  and  the  same 
phenomenon.  Bain,  for  example,  asserted  the  same  iden- 
tity of  activity  and  object  in  the  various  kinds  of  sense- 
impressions  as  he  believed  to  exist  in  the  so-called  affective 
sensations.  A closely  related  position  is  that  of  J.  S.  Mill. 
We  see  foreshadowed  here  the  concept  of  consciousness  as 
immediate  experience  in  which  the  two  terms  of  act  and 
content,  usually  kept  distinct,  are  identified,  as,  for  example, 
in  the  psychology  of  Wundt. 

Starting  from  his  own  point  of  view,  Brentano  undertook 
the  solution  of  the  problem  in  a different  manner.  He 
made  his  beginning  with  the  question  as  to  the  relation 
between  the  presentation  of  an  object  and  the  presentation 
of  this  presentation,  and  he  found  the  idea  of  a peculiar 
coalescence  of  the  object  and  its  accompanying  presenta- 
tion a common  one  among  psychologists.  Aristotle  had 
already  made  the  observation  that  a conscious  phenomenon 
must  include  within  itself  the  consciousness  of  itself.1  More 
clearly  than  in  the  case  of  sense-perception,  he  described 
the  peculiarity  of  inner  experience  in  his  Metaphysics  to  the 
effect  that  knowledge,  sensation,  opinion,  and  reflection  were 
always  directed  toward  something  else,  but  secondarily  also 
toward  themselves.  Practically  all  authorities  who  deny 
unconscious  activities  agree  with  this  description  in  the 
main.  So  J.  S.  Mill,  for  instance,  according  to  whom 
sensations  apprehend  themselves,  and  Lotze,  according  to 
whom  a consciousness  of  psychical  phenomena  accompanies 
the  phenomena.  Ulrici,  too,  regarded  all  our  sensations  as 
at  the  same  time  sensations  of  ourselves;  and  even  in 
Beneke  the  accompanying  consciousness  was  treated  as  a 
special  attribute  of  the  psychical  phenomenon,  given  with 
the  latter.2  In  Brentano’s  psychology,  after  the  statement 
that  every  psychical  phenomenon  is  the  consciousness  of 

1 De  Anima,  III,  p.  2.  2 Lehrb.  d.  Psych.,  2d  ed.,  § 57. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  181 


an  object,  the  opposite  question,  whether  every  psychical 
phenomenon  is  the  object  of  consciousness,  is  raised  in 
the  paradoxical  form  whether  an  unconscious  conscious- 
ness exists.  If  the  term  unconscious  is  here  understood 
in  the  passive  sense  of  an  object  of  which  one  is  not 
conscious,  an  unconscious  consciousness  is  as  free  from  con- 
tradiction, as,  for  example,  an  unseen  act  of  seeing.1  An- 
alysis, however,  tended  to  abandon  the  notion  of  an  un- 
conscious consciousness  in  the  above  sense,  since  it  showed 
that  the  presentation  of  a tone,  for  example,  and  the  pres- 
entation of  this  presentation  are  one  and  the  same  thing.2 
The  foundation  seemed  thus  to  be  removed  from  under  the 
notion  of  the  unconscious  from  the  standpoint  of  the  pure 
phenomenology  of  consciousness  also. 

3.  The  Range  of  Consciousness 

Aside  from  these  attempts  to  draw  the  boundary-lines 
of  consciousness,  certain  other  considerations  regarding  the 
range  of  consciousness  have  been  of  no  less  importance. 
While  the  determination  of  the  boundaries  of  conscious- 
ness tended  naturally  to  become  a speculative  question,  the 
problem  of  this  content  of  consciousness  tended  from  the 
first  to  take  on  an  empirical  and  special  character  and  pre- 
ceded to  some  extent  the  development  of  the  concept  of 
consciousness  itself. 

The  fact  that  only  a limited  number  of  psychical  contents 
could  be  present  in  consciousness  simultaneously  forced  it- 
self upon  the  attention  of  observers  at  a very  early  stage 
of  scientific  reflection.  Diogenes  of  Apollonia  is  reported 
to  have  referred  to  a competition  among  the  various  sense 
departments  for  a part  in  a limited  amount  of  mind  stuff.3 

1 Op.  cit.,  p.  133.  2 Op.  cit.,  p.  167. 

3 For  a history  of  the  attempts  to  determine  the  range  of  conscious- 
ness, see  W.  Wirth,  Die  experimentelle  Analyse  der  Bewusstseinspha- 
nomene,  1908,  pp.  56  ff. 


182 


HISTORY  OF  PSYCHOLOGY 


For  a long  time  scientific  curiosity  regarding  the  problem 
in  question  seems  to  have  been  satisfied  by  the  assertion 
of  Aristotle  that  several  objects  could  be  apprehended 
simultaneously,  to  which  he  added  certain  other  observa- 
tions concerning  the  relation  of  similar  and  opposite  ideas.1 
It  was  not  until  the  time  of  Scholasticism  that  we  find  in 
John  Buridan  a more  careful  investigation  of  the  possibility 
of  a plurality  of  simultaneously  existing  psychical  states.2 
Buridan  asked  the  question,  a question  new  to  his  time, 
as  to  the  degree  of  clearness  with  which  simultaneous  pres- 
entations could  be  perceived.  Now  every  perception,  no 
matter  how  simple,  is  composed  of  a multiplicity  of  parts. 
As  a rule,  it  is  not  the  parts  which  are  perceived,  but  the 
whole.  When  the  object  is  very  large,  on  the  other  hand, 
the  parts  are  perceived  more  distinctly  than  the  whole.  If 
a number  of  sensations  are  presented  simultaneously  the 
distribution  of  clearness  among  them  is  not  uniform.  These 
observations  of  Buridan,  fragmentary  as  they  are,  stand 
out  in  clear  relief  against  the  attempt  often  made  in  the 
Middle  Ages  to  limit  thought  ( intelligere ) to  one  presenta- 
tion at  a time,  an  idea  revived  in  the  Herbartian  school  of 
psychical  mechanics  and  ironically  called  the  needle-eye 
theory  of  consciousness. 

In  modern  psychology  the  problem  of  the  range  of  con- 
sciousness arose  in  connection  with  certain  epistemological 
distinctions  in  Locke,  to  whom  the  narrowness  of  con- 
sciousness was  a familiar  concept,  and  who  discussed  the 
psychological  distinctions  between  clear  and  obscure,  dis- 
tinct and  confused  ideas.3  A chiliahedron  and  a figure  of 
nine  hundred  and  ninety-nine  sides  can  be  distinguished  if 
we  confine  ourselves  to  that  part  of  the  two  ideas  indicated 
by  the  final  digits,  as,  for  example,  when  we  consider  that 

1 See  p.  89.  2 De  sens.,  21. 

3 Essay  on  the  Human  Understanding,  II,  chap.  XXIX,  esp.  § 14. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY 


183 


the  number  of  sides  is  divisible  by  two  in  the  one  case  and 
not  in  the  other.  A difficulty  arises,  however,  when  we  try 
to  distinguish  the  two  figures  by  their  actual  appearance  in 
perception,  since  we  can  form  no  distinct  images  of  the  two 
figures  in  the  mind,  as  we  can,  for  instance,  of  a figure  of  four 
and  one  of  five  sides.  Aside  from  the  insight  that  there  was 
some  sort  of  limit  to  the  number  of  clear,  simple  ideas  con- 
tained within  a complex  idea,  the  statement  that  this  limit 
was  not  exceeded  by  four  or  five  such  component  parts  has 
acquired  a special  significance  from  later  experimental  veri- 
fications. 

With  much  sympathy  and  intelligence  Bonnet  subse- 
quently undertook  to  deal  with  the  question,  which  arose 
in  many  different  connections,  as  to  whether  a number  of 
presentations  could  appear  in  consciousness  simultaneously. 
He  took  a decided  stand  against  the  Wolffian  school,  which 
tended  to  take  the  older  Scholastic  view  of  the  restricted 
range  of  consciousness.  The  arguments  of  the  Wolffians 
were  partly  metaphysical,  as  when  they  reasoned  that  it 
would  contradict  the  notion  of  the  simplicity  of  the  soul  if  it 
could  be  modified  variously  at  one  and  the  same  time;  they 
were  partly  based  upon  the  consideration  of  the  temporal 
succession  of  ideas  in  consciousness,  which  made  it  impos- 
sible for  more  than  one  idea  to  arise  in  a given  moment 
of  this  temporal  series.  Bonnet,  on  the  contrary,  asserted 
that  all  the  higher  psychical  processes,  the  intellectual  as 
well  as  the  conative,  presuppose  the  existence  of  a plurality 
of  simultaneous  ideas  in  consciousness.  Bonnet’s  observa- 
tions are  significant  also  for  the  distinction  drawn  by  him 
between  the  range  of  consciousness  and  the  range  of  atten- 
tion. In  the  visual  field,  for  instance,  a large  part  of  the 
contents  of  focalized  consciousness  shows  an  approximately 
even  distribution  of  clearness.1  For  the  determination  of 
1 Essai  de  Psychologie,  1755,  chap.  XXXVIII. 


184 


HISTORY  OF  PSYCHOLOGY 


the  range  of  attention  Bonnet  depended  upon  the  same 
method  which  had  earlier  led  Locke  to  assert  the  impos- 
sibility of  imagining  a chiliahedron.  He  stated  it  as  a 
constant  of  visual  imagination  that  only  five  or  six  simple 
contents,  like  the  sides  of  a geometrical  figure,  could  be 
grasped  simultaneously  with  a maximum  of  attention. 

The  first  attempts  at  an  experimental,  quantitative  de- 
termination of  the  range  of  consciousness  were  made  by 
Sir  William  Hamilton.1  Hamilton  sought  to  ascertain  how 
many  instantaneously  presented  visual  stimuli  could  be 
grasped  at  once,  evidently  proceeding  on  the  assumption 
that  the  range  of  consciousness  could  be  determined  by 
simply  counting  the  objects,  like  balls,  for  instance,  which 
had  been  momentarily  exposed.  It  was  not  until  much 
later  that  it  became  clear  that  what  Hamilton  was  investi- 
gating was  not  the  range  of  consciousness  but  the  range  of 
attention.  Hamilton’s  constant,  meanwhile,  which  never 
exceeded  six  impressions,  has  not  only  not  been  modified 
by  later  investigations,  but  it  approximates  also  the  earlier 
results  obtained  by  purely  introspective  methods,  in  spite 
of  the  fact  that  the  conditions  of  Hamilton’s  investiga- 
tions were  very  different  from  those  of  Bonnet’s,  since  in 
Hamilton’s  experiments  a degree  of  consciousness  sufficient 
for  reproduction  had  to  be  attained,  while  Bonnet  sought 
to  ascertain  the  greatest  possible  range  of  simultaneously 
presented  ideational  contents. 

4.  The  Graduation  of  Consciousness:  Attention 

One  of  the  most  general  characteristics  of  consciousness 
is  described  by  the  fact  that  within  the  field  of  conscious 
contents  as  a whole  a narrower  circle  of  so-called  contents 
of  consciousness  rises  into  comparative  prominence.  The 
1 Lectures  on  Metaphysics  and  Logic , I,  p.  254. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  185 


graduation  of  consciousness  according  to  degrees  of  clear- 
ness was  already  a familiar  aspect  of  the  concept  of  con- 
sciousness in  Leibniz,  and  the  genesis  of  the  notion  of  de- 
grees of  clearness  in  the  Leibnizian  psychology  has  already 
received  some  attention  in  previous  pages.1  The  relation 
existing  between  the  fluctuation  of  attention  and  the  clear- 
ness of  conscious  contents  was  also  presupposed  in  the  ear- 
lier efforts  to  construct  a theory  of  psychical  mechanics. 
It  was  Herbart  who,  starting  with  the  conception  of  a 
competition  among  ideas  and  refining  upon  the  Leibniz- 
ian terminology,  designated  the  ideas  showing  the  greatest 
amount  of  clearness  by  the  general  name  of  apperception. 

A new  point  of  departure  for  the  consideration  of  the 
problem  of  attention  grew  out  of  the  connection  of  the 
problem  of  attention  with  that  of  abstraction,  a connection 
which  maintained  itself  for  many  centuries  in  the  form  of 
the  so-called  empirical  theories  of  abstraction.  In  contrast 
with  the  antiquity  of  the  problem  of  abstraction,  which 
goes  back  to  the  early  beginnings  of  the  doctrine  of  general 
ideas,  attempts  to  give  a psychological  account  of  abstrac- 
tion belong  to  comparatively  recent  times.2  Oddly  enough, 
we  meet  with  them  in  a work  conceived  in  the  spirit  of 
Cartesian  rationalism,  the  Logique  de  Port-Royal .3  The 
distinction  is  here  made  between  the  abstract  and  the 
general.  The  abstraction  made  in  connection  with  a single 
object  is  a preparatory  step  toward  generalization  proper. 
On  account  of  the  circumscribed  scope  of  consciousness  it 
is  able  to  grasp  a complex  object  only  by  viewing  separately 
the  various  sides  which  the  object  presents.  This  isolation 
of  the  separate  sides  of  the  object  through  abstraction  is 
thus  characteristically  brought  into  connection  with  the 

1 See  p.  171,  above. 

2 Cf.  K.  Mittenzwey,  in  Wundt,  Psychologische  Studien,  II,  1907, 
p.  358. 

3 L’art  de  penser,  1662.  Edit.  nouv.  par  Fouille,  1879. 


186 


HISTORY  OF  PSYCHOLOGY 


narrowness  of  consciousness.  Great  as  was  Locke’s  sub- 
sequent contribution  to  the  description  of  the  processes  of 
abstraction,  he  never  succeeded  in  giving  a psychological 
explanation  of  the  activities  in  question.  It  is  true  that  he 
specially  mentioned  the  fact  (to  use  his  own  illustration) 
that  the  mind  observes  the  same  color  in  chalk  or  snow 
to-day  that  it  yesterday  received  from  milk.  But  the  rea- 
son for  this  he  never  gave.1  A purely  empirical  solution 
of  the  problem  as  to  the  manner  in  which  this  abstraction 
takes  place  was  given  by  Hume.  When  we  distinguish  the 
form  of  a body  from  its  color  we  view  the  body  from  the 
different  points  of  view  which  result  from  the  different  se- 
ries of  resemblances  into  which  the  characteristics  observed 
arrange  themselves.2  With  this  the  problem  of  abstraction 
was  solved  to  the  extent  that  the  older  question  of  generali- 
zation gave  way  to  that  of  abstraction  in  the  case  of  the  sin- 
gle presentation.  The  nature  of  this  process  of  abstraction, 
however,  reduced  itself  again  in  Hume  to  the  play  of  the 
mechanism  of  association. 

A new  phase  of  the  problem,  developed  in  contemporary 
French  psychology,  brought  the  process  of  abstraction  into 
relation  with  that  of  attention.  The  idea  that  attention 
isolates  a given  sense  quality  from  the  rest,  thus  resulting 
in  abstraction,  goes  back  to  Condillac.  In  its  essential 
features  this  view  was  still  represented,  at  the  beginning  of 
the  nineteenth  century,  by  Laromiguiere.3 

More  important  were  the  attempts  of  Bonnet  to  make 
an  analysis  of  the  process  of  attention,  although  he  still 
depended  largely  upon  the  ideas  of  the  nerve-fibre  psychol- 
ogy.4 The  distinction  between  sensation  and  reflection  as 
two  different  sources  of  ideas  Bonnet  derived  from  the  psy- 

1 An  Essay  on  the  Human  Understanding,  II,  chap.  XI,  p.  9. 

2 Treatise  of  Human  Nature,  I,  § VII. 

3 Logons  de  philosophic,  II,  3d  ed.,  1823,  p.  321. 

i Gf.  p.  94,  above. 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  187 


chology  of  his  time.  The  ideas  of  reflection  arise  in  conse- 
quence of  the  action  of  attention  upon  the  nerve-fibres  with 
which  the  ideas  in  question  are  associated.  That  true 
perception  arises  only  in  this  way  Bonnet  illustrates  by  the 
example  of  a preoccupied  philosopher  who  is  taking  a walk 
through  the  woods.  Most  of  the  impressions  from  his  sur- 
roundings glide  over  the  surface  of  his  consciousness,  only 
those  attracting  the  attention  which  are  important  for  his 
welfare.1  Bonnet’s  theory  of  abstraction,  with  its  emphasis 
upon  attention,  has  in  its  main  features  served  as  a model 
for  many  other  treatments  of  the  subject.  In  Germany, 
Lossius  interpreted  it  in  a peculiar  manner  in  terms  of 
physiological  processes.2  Since  the  soul  is  unable  to  think 
without  the  action  of  nerve-fibres,  even  general  concepts 
must  have  physiological  correlates.  In  three  partially 
identical  presentations,  Am,  An,  and  Ap,  A is  represented 
by  a common  nerve-fibre.  If  this  is  excited  alone,  the 
result  is  a general  idea  common  to  all  three  presentations. 

Through  such  reinterpretations  the  empirical  theory  of 
abstraction  became  pretty  far  removed  from  the  psycho- 
logical problem  of  attention.  The  insight  into  the  connec- 
tion between  the  isolation  of  mental  contents  accomplished 
through  attention  and  the  distribution  of  degrees  of  clear- 
ness was  reserved  for  English  psychology.  We  meet  it  in 
the  turn  which  Hamilton  gave  to  the  problem  of  abstraction. 
Whether  considerations  of  this  kind  had  any  significance 
for  the  logical  side  of  the  problem  of  abstraction  is  not  im- 
portant here.  What  is  of  importance  for  the  doctrine  of 
attention  is  the  process  of  abstraction  in  the  sense  of  the 
isolation  of  the  contents  observed,  and  Hamilton  located 
the  central  point  of  the  problem  by  bringing  it  into  relation 
to  the  circumscribed  scope  of  consciousness.  Since  atten- 

1 Cf.  J.  Speck,  Arch.  f.  Gesch.  d.  Phil.,  XI,  1898,  p.  181. 

2 Physische  Ursachen  des  Wahren,  pp.  156  ff. 


188 


HISTORY  OF  PSYCHOLOGY 


tion  can  grasp  only  a small  number  of  impressions  simul- 
taneously, and  these  only  imperfectly,  the  turning  of  the 
attention  toward  a given  impression  means  the  withdrawal 
of  it  from  the  rest.1  Meanwhile,  attention  is  described  as  a 
will  act  conforming  to  a definite  psychological  law,  the  law, 
namely,  that  the  greater  the  number  of  impressions  simul- 
taneously presented  to  consciousness  the  less  the  intensity 
with  which  each  of  the  separate  impressions  is  felt.  Atten- 
tion was  thus  recognized  as  consciousness  of  a higher  degree 
or  strength.  It  is  true  that  we  still  have  an  identifica- 
tion of  the  range  of  attention  with  that  of  consciousness.2 
Nevertheless,  the  two  characteristics  which  Hamilton  found 
in  the  experience  of  attention,  namely,  the  increased  clear- 
ness which  attention  involves  and  the  close  relation  of  at- 
tention to  will,  have  been  incorporated  into  the  modern 
concept  of  attention  as  its  most  important  characteristics. 
Freed  from  its  long  entanglement  with  the  problem  of 
abstraction,  the  concept  of  attention  or  apperception  has 
become  one  of  the  fundamental  concepts  of  psychology, 
illustrating  not  only  an  elementary  aspect  of  consciousness 
but  the  simplest  form  of  conation  as  well. 

To  what  extent  experimental  methods  have  entered  this 
field  is  illustrated  by  the  work  of  W.  Wirth,  whose  exper- 
imental investigations  were  based  on  the  thought  that  an 
exact  determination  of  degrees  of  consciousness  could  be 
obtained  from  the  apperceptively  conditioned  changes  in 
psychical  magnitudes,  such,  for  example,  as  a difference- 
threshold. 

The  most  important  result  of  the  evolution  of  the  con- 
cept of  consciousness  as  a whole  is  the  extension  of  the 
narrower  connotation  of  consciousness  as  inner  awareness 
to  include  the  whole  phenomenological  constitution  of  the 

1 Lectures  on  Meta-physics  and  Logic,  5th  ed.,  1870,  p.  258. 

2 Cf.  p.  184.' 


THE  SUBJECT-MATTER  OF  PSYCHOLOGY  189 


ego,  or  the  totality  of  psychical  experiences.  In  this  way 
the  concept  of  experience  was  extended  beyond  its  original 
meaning  as  the  inwardly  perceived  so  as  to  include  what  the 
ego  actually  constructs.  The  difficulty,  however,  that  the 
ego  of  pure  apperception  in  the  Kantian  sense,  as  the  locus 
of  relations  for  all  conscious  contents,  cannot  itself  be  a 
conscious  content  standing  on  a level  with  other  contents 
has  given  rise  to  serious  misgivings.1  This  difficulty  has 
only  recently  led  Natorp  to  argue  that  consciousness  means 
object  for  an  ego  and  that  this  object  relation  cannot  again 
become  an  object.  In  order  to  solve  this  difficulty,  a num- 
ber of  psychologists  have  suggested  a new  definition  of  con- 
sciousness according  to  which  consciousness  is  a general 
term  for  psychical  activities.2  Now,  these  activities  can  be 
directed  upon  the  phenomenological  ego  just  as  w7ell  as  upon 
other  objects.  This  shift  in  the  meaning  of  the  concept  of 
consciousness  wdiich  the  purely  descriptive  efforts  of  these 
psychologists  effected  brings  us  to  the  subject  of  the  clas- 
sification of  the  contents  of  consciousness. 

1 Cf.  p.  179,  above. 

2 E.  Husserl,  Logische  Untersuchungen,  II,  p.  342. 


CHAPTER  YII 


CLASSIFICATION  OF  THE  CONTENTS  OF  CONSCIOUSNESS 

Attempts  to  classify  psychical  phenomena  according  to 
their  chief  differences  arose  at  a much  earlier  period  than 
the  formation  of  a concept  which  would  express  their  com- 
mon characteristic,  namely  the  concept  of  consciousness. 
The  differences  in  the  content  of  consciousness  forced  them- 
selves on  the  attention  first  of  all,  long  before  their  common 
participation  in  one  unified  conscious  existence  was  noticed. 
The  older  classifications  were,  therefore,  not  made  on  the 
same  basis  as  the  later  ones.  For  these  latter  were  based 
upon  characteristics  which  only  appear  when  the  separate 
psychical  contents  are  regarded  as  being  contents  of  con- 
sciousness belonging  to  one  whole.  Nevertheless,  the  striv- 
ing toward  an  appropriate  classification  of  the  contents  of 
consciousness  has  always  been  in  psychology  the  sign  for 
the  rise  of  empirical  thought. 

The  individual  classifications  of  varying  extent  with 
which  psychology  busied  itself  are  subordinate  to  the 
problem  of  a general  classification  of  the  contents  of  con- 
sciousness, which  deals  with  the  highest  classes  or  genera 
of  the  contents  of  consciousness.  Now,  if  a classification 
is  built  upon  ideas  of  similarity,  it  generally  becomes  am- 
biguous, since  each  content  of  consciousness  may  be  grouped 
differently  according  to  different  ideas  of  similarity.  What 
determines  the  grouping  is  the  choice  of  a definite  principle 
of  classification.  We  can,  therefore,  best  orient  ourselves 
by  means  of  a survey  of  the  most  important  principles  of 

190 


THE  CONTENTS  OF  CONSCIOUSNESS 


191 


classification  upon  which  in  the  history  of  our  subject  the 
attempts  at  classification  have  been  based.  Many  of  these 
principles  are  still  exerting  their  influence  at  the  present 
day.  This  is  especially  the  case  with  that  principle  out  of 
which  the  concept  of  a psychical  element  has  arisen — a 
concept  that  has  been  so  important  in  modern  classifica- 
tions. 


i.  Survey  of  the  Most  Important  Principles  of 
Classification 

Before  the  application  of  empirical  principles  of  classi- 
fication we  find  many  primitive  attempts  to  do  justice  to 
the  diversity  of  psychical  facts.  The  metaphysical  psy- 
chology, to  which  the  problem  of  classification  was  really 
foreign,  was  inclined  most  often  to  dispose  of  it  by  presup- 
posing different  substrata  for  the  phenomena.  In  the 
theory  of  the  divisions  of  the  soul,  the  necessity  for  classi- 
fication finds  a naive  expression,  inasmuch  as  the  principle 
of  unity  in  regard  to  the  experiences  of  each  such  division 
of  the  soul  is  maintained.1 

The  empirical  classifications  can  be  arranged  under  three 
heads.  Most  often  the  principle  of  non-derivability  has 
been  used,  according  to  which  the  highest  classes  were 
formed  of  contents  of  consciousness  which  could  not  be 
derived  from  each  other.  Under  this  head  comes  also  the 
differentiation  of  the  contents  according  to  their  origin,  in 
so  far  as  their  non-derivability  is  an  immediate  consequence 
of  the  difference  of  their  origin.  Not  so  openly  acknowl- 
edged and,  therefore,  more  often  unconsciously  effective, 
is  the  principle  of  intentional  relationship,  by  means  of 
which  the  fundamental  divisions  are  made  according  to  the 
way  in  which  the  contents  of  consciousness  are  related  to 

1 Cf.  p.  46. 


192 


HISTORY  OF  PSYCHOLOGY 


their  intentional  object.  Superior  to  these  two  principles 
is,  lastly,  the  principle  of  analysis,  which  takes  as  its  point 
of  departure  the  division  of  all  contents  of  consciousness 
into  complex  and  simple. 

(a)  The  Rise  of  Psychological  Classification 

The  division  of  conscious  experiences  was  suggested  in 
the  first  instance  by  expressions  used  in  speech.  For  a long 
time  this  motive  for  classification  escaped  psychological 
analysis,  as  is  seen  in  the  ramifications  of  the  old  faculty 
psychology.  In  the  earliest  divisions  of  metaphysical  psy- 
chology we  note  that  here  also  non-scientific  points  of  view 
dominate,  mostly  in  the  form  of  analogies  with  principles 
of  division  that  man  had  employed  upon  the  things  of  his 
environment.  The  threefold  division  is  an  ancient  pos- 
session of  mankind.  Even  the  Indian  theory  of  the  soul 
mentions  three  kinds  of  psychical  content:  (1)  Guna,  or 
spirit,  also  called  satva  (sense  of  truth)  or  atman  (breath); 
(2)  radschas  or  manas  (energy),  also  called  ahankara  (feel- 
ing of  self);  (3)  tamas  (darkness),  as  the  symbol  of  pas- 
sion or  desire.  This  threefold  division  is  a connecting-link 
in  a long  chain  of  analogy,  which  begins  with  the  three 
gods,  Indra,  Varuna,  and  Agni,  is  continued  in  the  three 
elements  of  nature — light,  air,  and  earth — and  which  ulti- 
mately terminates  in  the  threefold  division  of  society  into 
Brahmans,  or  priests;  Kschatrijas,  or  warriors;  and  Vaigjas, 
or  workers.  Similarly  the  twofold  division  into  higher  and 
lower  functions  of  the  soul  corresponds  to  the  pairs  of  oppo- 
site words  found  almost  in  every  language,  as  in  Hebrew 
ruach  and  nephesch,  in  Greek  wfi?  and  tyoxv,  in  Latin  animus 
and  anima,  and  in  Slavonic  languages  duch  and  duse.1  In 
the  older  divisions  of  Greek  psychology  ethical  considera- 
1 0.  Willmann,  Empirische  Psychologie,  1904,  pp.  11  ff. 


THE  CONTENTS  OF  CONSCIOUSNESS 


193 


tions  join  with  these  language  influences  and  help  determine 
the  division.  Plato’s  division  was  based  upon  the  two  chief 
differences  in  the  direction  of  moral  strife  and  expressed 
clearly  the  conflict  between  the  demands  of  reason  and 
those  of  the  sensual  desires  in  man. 

The  classifications  of  Aristotle  are  the  first  that  begin  to 
show  some  understanding  of  the  peculiar  nature  of  psychic 
content.  Of  his  principles  of  division,  that  one  has  most 
psychological  importance  according  to  which  he  divides 
psychical  activities  in  relation  to  their  object.  In  Scholas- 
tic terms,  it  is  the  method  of  intentional  in-existence  that 
causes  the  difference  between  thinking  and  desiring.  These 
two  activities  are  not  directed  toward  different  objects  but 
toward  the  same  object  in  a different  manner.  The  same 
thing  may  be  at  once  object  of  thought  and  of  desire.1  The 
decisive  characteristic  is  no  longer  the  difference  in  the 
substratum,  or  bearer,  but  rather  the  relation  to  the  inten- 
tional object.  With  this  we  see  the  foundation  of  a prin- 
ciple of  differentiation  that  has  been  dominant  for  many 
centuries. 

The  ideational  and  the  volitional  worlds  were  in  this  way 
empirically  separated.  The  effect  of  this  point  of  view  of 
intentional  relationship  is  seen  in  the  fact  that  that  group  of 
experiences  which  do  not  so  readily  show  such  a relation- 
ship, i.  e.,  the  feelings,  were  neglected  in  this  classification, 
and  only  very  much  later  were  they  recognized  as  a special 
psychical  division.  We  owe  the  first  thoroughgoing  psy- 
chological description  of  the  affective  experiences  to  Augus- 
tine. Influenced  probably  by  his  own  enhanced  affective 
life,  he  grouped  the  feelings  in  an  independent  division 
alongside  of  ideas  and  will.2  In  the  Middle  Ages,  however, 

1 Be  Anima,  III,  10;  Metaphysics , XII,  7. 

2 Cf.  Siebeck,  Beitrage  zur  Entstehungsgeschichte  der  neueren  Psycho- 
logic, Giessen,  1871. 


194 


HISTORY  OF  PSYCHOLOGY 


these  beginnings  were  lost  sight  of  because  of  the  dominance 
of  the  Aristotelian  twofold  division.  In  Thomas  Aquinas’s 
famous  theory  of  the  emotions  we  find  simply  the  tradi- 
tional opinion  that  feeling  is  only  a modification  of  desir- 
ing. A separation  of  the  feelings  from  the  volitional  proc- 
esses begins  first  of  all  with  Duns  Scotus,  who  classed 
pleasure  and  pain  as  “passions,”  and  differentiated  them 
from  acts  of  will. 

The  speculations  of  the  German  mystical  philosophers 
arrived  in  quite  a different  fashion  at  an  understanding  of 
the  affective  processes.  It  is  true  that  these  mystics  had  a 
great  many  problems  in  common  with  Scholastic  philosophy, 
but  they  experienced  these  problems  differently.  Master 
Eckhart  started  with  the  discussion  whether  the  will  or 
the  intellect  was  the  superior  power,  and  he  settled  this 
in  his  own  peculiar  fashion  by  lapsing  into  an  emotional 
state  beyond  will  and  intellect  in  which  both  of  the  latter 
coalesced  into  one  unity.  Since  Scholastic  philosophy  had 
no  expression  for  such  experiences,  he  coined  the  word 
Gemiit.1  This  was  the  signal  for  the  further  naming  and 
emphasizing  of  the  affective  experiences.  It  was  a long 
time,  however,  before  scientific  psychology  was  at  all  influ- 
enced by  these  important  presentiments  of  the  pious  mystics. 

( b ) The  Principle  of  Non-Derivability 

The  new  concept  of  consciousness  made  possible  the  con- 
ception of  psychical  phenomena  as  belonging  to  an  inde- 
pendent field  of  experience,  and  from  this  conception  there 
arose  a number  of  different  points  of  view  for  purposes  of 
classification.  Only  after  consciousness  had  been  found 
to  be  a common  characteristic  of  psychical  contents  could 

1 [“Feeling  and  Will;  the  Sum  Total  of  Affective-Conative  Processes,” 
Titchener,  Am.  J.  of  Psych.,  VII,  p.  81.  Trs.] 


THE  CONTENTS  OF  CONSCIOUSNESS 


195 


the  content  of  consciousness  be  classified  according  to  purely 
phenomenological  attributes.  This  new  standpoint  is  clearly 
seen  in  Locke’s  classification  of  the  contents  of  conscious- 
ness. 

Locke  first  of  all  divided  his  “ideas,”  which  coincide  with 
our  modern  conception  of  the  contents  of  consciousness, 
into  complex  and  simple,  and  classified  the  latter  accord- 
ing to  their  origin,  that  is  to  say,  according  to  the  manner 
in  which  they  enter  into  consciousness.  This  principle  of 
classification  naturally  came  to  him  because  he  had  pre- 
supposed that  the  mind  was  at  first  absolutely  blank,  a 
tabula  rasa.  In  this  manner  he  arrived  at  the  following 
four  classes:1  (1)  Ideas  that  come  into  the  mind  by  one 
sense  only  (simple  sensations) ; (2)  ideas  that  come  into  the 
mind  by  more  senses  than  one  (e.  g.,  extension,  form);  (3) 
ideas  that  are  to  be  had  only  from  reflection  or  introspection 
(thinking  and  willing);  (4)  ideas  that  are  suggested  to  the 
mind  by  all  the  ways  of  reflection  and  sensation  (e.  g.,  plea- 
sure, existence,  energy,  time). 

The  greatest  misgivings  arise,  of  course,  in  regard  to  the 
last  class.  The  differentiation  between  ideas  of  reflection 
and  those  that  enter  the  mind  by  means  of  sensation  points 
forward  to  the  later  differentiation  between  the  subjective 
and  objective  sides  of  consciousness.  Again,  Locke’s  method 
of  first  considering  the  simple  ideas  became  common  in 
much  of  the  psychology  from  his  day  onward.  His  simple 
ideas  are  already  elements  in  the  sense  that  they  can  neither 
be  produced  nor  destroyed  by  the  mind.  They  are  things 
given  to  us  in  experience,  and  when  this  is  not  the  case  they 
cannot  be  produced  by  any  power  of  even  the  most  sublime 
genius.2  We  must  also  remember  that  the  different  origin 
of  these  classes  of  ideas  brings  with  it  their  reciprocal  non- 

1 Essay  on  the  Human  Understanding,  II,  chap.  Ill,  § 1. 

2 Op.  cit.,  chap.  II,  § 2. 


196 


HISTORY  OF  PSYCHOLOGY 


derivability,  which  is  caused  by  the  simple  character  of  these 
ideas.  We  find,  therefore,  in  Locke  the  origins  of  the  most 
important  points  of  view  which  have  been  used  in  later 
psychological  classifications. 

Nevertheless,  in  spite  of  all  this,  the  old  Aristotelian  two- 
fold division  into  thinking  and  willing  continued  to  exist 
for  a long  time.  It  was,  in  fact,  the  chief  ground  of  division 
in  the  psychology  of  Wolff,  who  also  used,  in  addition  to 
this,  the  popular  division  into  higher  and  lower  activities  of 
the  soul.  In  English  psychology  Hume  continued  the  two- 
fold division,  and  it  was  retained  right  down  to  the  time  of 
Reid  and  Brown.  The  latter  subordinated  it,  however,  to 
the  division  of  all  content  into  outer  and  inner  affections: 
the  first  class  comprised  all  sense-perceptions,  and  the 
second  contained  intellectual  mental  states  and  affective 
states  (moral  phenomena). 

It  was  not  until  the  psychology  of  the  German  Enlighten- 
ment that  a new  terminology  came  into  being.  In  Tetens 
and  Mendelssohn1  feeling  is  recognized  as  a third  class 
alongside  of  intellectual  and  volitional  processes.  Tetens 
separates  sensation  and  feeling  clearly,  inasmuch  as  he 
explains  the  former  as  a copy  of  the  object  and  the  latter 
as  a change  in  the  perceiving  subject.2 

A more  thoroughgoing  foundation  for  the  division  into 
knowing,  feeling,  and  willing  is  found  in  Kant,  especially 
in  his  treatise  entitled  Uber  Philosophic  uberhaupt,  which 
gives  the  best  summary  of  his  general  psychological  views. 
These  classes,  he  maintains,  are  fundamental  for  the  rea- 
son that  they  are  neither  derived  from  each  other  nor  can 
any  one  be  traced  back  to  the  other.  Such  a method  of 
reasoning  was  peculiarly  adapted  to  the  old  faculty  psy- 
chology, because  the  phenomena,  the  sum  total  of  which 

1 Gesammelle  Schriften,  II,  p.  295. 

2 Philosophische  Versuche,  I,  pp.  214/. 


THE  CONTENTS  OF  CONSCIOUSNESS 


197 


went  to  form  such  a class,  were  considered  a 'priori  as  effects 
of  a single  faculty  and,  as  such,  had  to  resemble  each  other 
to  a very  great  extent.  The  faculties  themselves,  however, 
had  to  be  independent  and  absolutely  heterogeneous  if  dif- 
ferences in  mental  life  found  in  our  inner  experience  were 
to  be  explained  by  their  activity. 

In  so  far  as  the  discussion  of  this  division  was  carried  on 
in  the  Kantian  school  from  the  standpoint  of  the  faculty 
psychology  it  loses  interest  for  us.  Krug,  for  example, 
maintained  that  only  two  faculties  were  necessary,  namely, 
ideation  and  endeavor,  because  the  activity  of  the  human 
mind  was  exerted  in  two  directions — outward  and  inward. 
It  was  Hamilton,  however,  who  gave  a more  serious  vindi- 
cation of  the  Kantian  classification.  He  strove  to  justify 
the  position  that  feeling  should  be  considered  as  an  inde- 
pendent class,  since  there  exist  states  of  consciousness  that 
cannot  be  classified  as  belonging  either  to  thought  or  to 
active  endeavor.1  In  spite  of  this  co-ordination  of  the  three 
classes  there  remained,  nevertheless,  an  order  of  prece- 
dence, in  which  knowing  took  the  first  place.  For,  if  we 
consider  which  one  of  the  three  classes  is  least  dependent 
on  the  others,  it  is  at  once  clear  that  knowing  is  the  only 
one  that  could  lay  claim  to  be  an  independent  entity.  In 
the  second  place  comes  feeling,  which  can  at  least  be  thought 
of  as  taking  place  without  volitional  processes.  The  re- 
maining class  always  presupposes  the  co-operation  of  the 
two  others.2 

After  Herbart’s  attempt  to  abolish  all  multiplicity  of  men- 
tal faculties  it  was  Lotze  who  was  most  pronounced  in  his 
defense  of  the  Kantian  threefold  division.  He  did  not  wish 
or  attempt  to  support  that  strict  division  which  regarded 
knowing,  feeling,  and  willing  as  three  lines  of  development 

1 Lectures  on  Metaphysics,  II,  p.  423. 

2 Op.  cit.,  I,  p.  187;  II,  p.  431. 


198 


HISTORY  OF  PSYCHOLOGY 


absolutely  independent  of  each  other.  In  comparing  mental 
phenomena,  however,  he  was  driven  to  make  the  hypothesis 
that,  in  the  dependence  of  experiences  of  these  different 
classes  on  each  other,  the  first  process  acts  as  a kind  of 
inducing  motive  to  the  succeeding  process,  but  does  not 
cause  it,  while  at  the  same  time  there  is  some  power  or 
force  at  work  which  gives  its  assistance,  but  which  escapes 
our  observation.  If  the  soul  were  nothing  else  than  a think- 
ing or  imagining  being,  there  would  be  no  sufficient  reason 
why  anything  else  except  this  special  activity  should  be 
called  into  being.  There  would  be  no  reason  for  feelings 
of  pleasure  and  pain.  Any  inner  change,  however  dan- 
gerous it  might  be  for  the  soul’s  own  existence,  would  sim- 
ply be  observed  or  perceived  by  it,  just  as  it  simply  observes 
any  other  conflict  of  forces.1  This  description  of  Lotze  is 
worthy  of  note  because  it  is  an  attempt  to  give  a purely 
psychological  foundation  to  the  fundamental  thought  un- 
derlying the  Kantian  threefold  division. 

There  is  another  form  of  the  threefold  classification 
that  uses  for  its  general  principle  of  classification  the  pop- 
ular psychological  distinction  between  actual  sense-impres- 
sions and  their  reproduction  or  mental  images.  This  is 
not  met  with  so  often  in  the  history  of  psychology,  al- 
though just  such  a threefold  division,  which  regards  as 
ultimate  elements  sensations,  images,  and  feelings,  is  to  be 
observed  in  modern  psychology.2  If  we  pass  over  the 
primitive  explanation  which  was  satisfied  with  the  old  theory 
of  the  inner  sense,  inasmuch  as  it  referred  the  differences 
between  sensations  and  their  reproductions  to  the  outer 
and  inner  senses,3  we  see  at  once  that  this  question  was  not 
of  special  importance  for  faculty  psychology,  because  it 
was  presupposed  that  the  soul  had  an  immediate  conscious- 
ness of  its  different  activities.  Locke  wTas  content  merely 

1 Mikrokosmos,  I,  pp.  193  ff.  2 See  below,  2.  3 Cf.  pp.  71  /. 


THE  CONTENTS  OF  CONSCIOUSNESS 


199 


to  affirm  that  the  soul  was  passive  in  sensation  and  active 
in  reproduction.  This  same  opposition  occurs  again  in 
Leibniz,1  who  regarded  sensation  as  passive,  because  of  its 
vagueness,  and  the  image  or  thought  process  as  active. 

Purely  psychological  characteristics  for  such  a differen- 
tiation were  first  sought  by  the  English  Sensationalists. 
It  is  obvious  that  motives  prompted  by  their  theory  of 
knowledge  led  them  to  fix  upon  a clear  distinction  between 
sensation  and  the  reproduction  of  sensation.  Berkeley 
had  already  noted  a long  list  of  criteria  that  distinguished 
sensations  from  images:  intensity,  vivacity,  duration,  and 
orderly  coherence.2  And  Hume  also  attempted  in  different 
ways  to  make  it  clear  why  it  is  that  we  experience  mental 
images  as  different  from  sensations.  He  found,  for  example, 
that  the  most  vivid  reproduction  is  clearly  inferior  to  the 
most  vague  sensation.  This  is  an  opinion  that  Spencer 
repeated  a hundred  years  later.3  French  Sensationalism 
did  not  make  the  distinctions  quite  so  fine,  for,  following 
the  example  of  Condillac,4  the  difference  between  vivacity 
and  intensity  was  neglected,  and  the  two  were  considered 
identical.  Alongside  of  this  purely  psychological  determi- 
nation of  the  difference,  there  have  always  arisen  attempts 
at  a physiological  explanation.  Hartley  translated  Hume’s 
description  into  the  language  of  his  vibration  hypothesis, 
and  he  gave  it  the  interpretation  that  the  breadth  of  the 
oscillation  of  a sensation  always  exceeded  the  breadth  of 
the  oscillation  of  the  reproduction.  When  such  a naive, 
materialistic  explanation  was  no  longer  tenable,  the  oppo- 
sition between  the  sensory  and  motor  nervous  systems  was 
made  use  of,  as,  for  example,  in  the  writings  of  George, 
who  took  into  account  the  physiological  knowledge  of  the 
nineteenth  century. 

1 Monadologie,  49.  2 Treatise,  30. 

3 Principles  of  Psychology,  I,  § 49.  4 Traite  des  sensations,  I,  2,  9. 


200 


HISTORY  OF  PSYCHOLOGY 


The  problem  as  to  the  relation  between  sensation  and 
reproduction  is  solved  at  last  in  the  simplest  manner  by 
means  of  the  presuppositions  of  Herbart’s  psychology. 
Here  they  turn  out  to  be  simply  different  periods  in  the 
history  of  the  same  idea.  Sensation  is  the  idea  from  its 
development  to  its  first  disappearance,  and  reproduction 
is  the  idea  from  its  reappearance  in  consciousness  to  its 
next  disappearance.1 

Under  these  circumstances  there  was  no  decisive  motive 
that  might  lead  to  a division  of  sensation  and  image  into 
two  absolutely  independent  classes.  We  see,  therefore, 
that  the  most  universally  acknowledged  consequence  of 
the  principle  of  non-derivability  is  the  threefold  division 
into  feeling,  willing,  and  thinking. 


(c)  The  Principle  of  Intentional  Relationship 

The  principle  of  non-derivability  was  subjected  to  the 
keenest  criticism  by  Brentano,2  even  though  we  can  trace 
back  to  him  many  of  the  principles  mentioned  above.  If 
two  psychical  phenomena  are  to  be  looked  upon  as  belong- 
ing to  absolutely  different  classes,  simply  because  we  cannot 
a priori  draw  a conclusion  from  our  capacity  for  the  one  to 
our  capacity  for  the  other,  we  must  not  only,  along  with 
Kant,  Hamilton,  and  Lotze,  separate  thinking  from  feeling 
and  desiring  but  also  seeing  from  tasting.  Why,  we  must 
even  go  further  and  separate  red  vision  from  blue  vision 
as  from  a phenomenon  that  belongs  to  another  ultimate 
class.  In  fact,  if  we  look  closely,  we  see  in  those  thinkers 
the  unconscious  influence  of  the  characteristic  of  intentional 
in-existence  used  by  Aristotle  in  his  classification. 

Kant  makes  the  distinction  between  knowing  and  desir- 

1 For  this  description  see  Volkmann,  Lehrbuch  der  Psychologie,  I,  § 80. 

2 Psychologie  vom  empirischen  Standpunkte,  I,  pp.  246  ff. 


THE  CONTENTS  OF  CONSCIOUSNESS 


201 


mg  consist  of  a difference  in  their  relation  to  the  object; 
and  the  peculiarity  of  feeling  is  supposed  to  be  due  to  the 
fact  that  in  this  case  merely  a relation  to  the  subject  exists. 
Reciprocal  non-derivability  follows  as  a necessary  conse- 
quence of  this  difference  in  intentional  relation;  but  not  in 
all  cases  of  non-derivability  need  the  intentional  relation 
be  of  another  kind.  This  latter  principle  of  classification 
is,  therefore,  superior  to  the  other.  We  find  the  same 
opinion  in  Hamilton.  In  the  phenomenon  of  knowing, 
consciousness  distinguishes  between  a known  object  and  a 
knowing  subject;  in  the  case  of  the  feelings,  however,  con- 
sciousness is  itself  fused  with  the  psychical  state.  And, 
lastly,  in  the  case  of  desiring  or  willing  there  is,  just  as  with 
knowing,  a relation  to  an  object,  but  knowing  and  desiring 
are  differentiated  just  by  the  difference  in  their  relation  to 
the  object.  This  last  point  of  view  seems  to  have  been 
decisive  for  Hamilton.  The  man  who  most  thoroughly  fol- 
lowed out  the  consequences  of  this  principle  of  the  non- 
derivability  of  faculties  was  Lotze,  and  he  was  roused  to 
do  this  by  the  polemic  against  Herbart.  He  did  not  draw 
back  from  the  logical  consequences,  for  he  maintained, 
for  example,  that  the  faculties  of  seeing  and  hearing  were 
different,  original,  and  independent  faculties.1  And  yet, 
since  he  classed  the  images  of  tones  and  colors  in  the  same 
class,  it  would  seem  as  though  another  point  of  view  had 
been  at  work  in  his  division  into  three  classes. 

In  place  of  the  principle  of  non-derivability,  Brentano, 
therefore,  took  the  principle  of  intentional  relations  in  order 
to  determine  the  chief  classes  of  mental  phenomena.  He 
found  in  accordance  with  the  different  ways  of  intentional 
in-existence  three  main  classes — ideation,  judgment,  and 
emotion.  He  vindicated  this  division  by  appealing  to  inner 
experience,  and  held  that  within  the  same  class  the  relation 
1 Mikrokosmos,  I,  p.  198. 


202 


HISTORY  OF  PSYCHOLOGY 


of  consciousness  to  the  object  is  always  the  same  or  sim- 
ilar, whereas  between  the  classes  this  relation  is  essentially 
different.  For  the  separation  of  ideation  and  judgment, 
which  is  the  most  surprising  thing  in  this  new  threefold 
division,  Brentano  gave  an  indirect  proof.  If  no  such 
fundamental  difference  in  their  intentional  relations  existed, 
then  the  difference  must  lie  either  in  the  content,  to  which 
they  both  refer,  or  in  the  degree  of  perfection,  in  which  the 
same  content  may  exist  in  our  minds  as  ideation  or  as  judg- 
ment. Since,  however,  neither  of  these  is  the  case,  the 
difference  can  only  be  one  of  intentional  relation. 

This  threefold  division  is  connected  in  a peculiar  man- 
ner with  Brentano’s  theory  of  the  inner  consciousness. 
Each  psychical  act,  however  simple,  can  be  looked  upon  as 
idea  of  itself,  as  knowledge  of  itself,  and  as  feeling  of  itself. 
In  this  we  see  clearly  Brentano’s  striving  to  make  the 
three  kinds  of  intentional  relationship  the  necessary  forms 
by  means  of  which  anything  comes  to  consciousness  and 
thereby  give  his  three  chief  classes  a logical  connection 
in  conscious  life.  To  thoroughly  appreciate  this  classifica- 
tion, one  must  remember  his  concept  of  the  “psychical 
phenomenon”  1 in  which  the  use  of  this  principle  of  inten- 
tional relation  is  obviously  foreshadowed.  Besides  this, 
the  use  of  this  principle  gave  his  logical  tendencies  plenty 
of  scope,  inasmuch  as  the  most  important  function  of  logical 
thinking,  i.  e.,  judgment,  became  one  of  the  fundamental 
classes  of  the  mental  processes. 

(d)  The  Principle  of  Analysis 

When  we  call  to  mind  how  comparatively  late  in  the 
history  of  psychology  any  reflection  as  to  the  conditions 
of  psychological  analysis  arose,  we  cannot  be  at  all  surprised 

1 Cf.  p.  84. 


THE  CONTENTS  OF  CONSCIOUSNESS 


203 


that  the  distinction  between  simple  and  complex  contents 
of  consciousness  is  of  recent  origin.  Along  with  this  there 
are  the  peculiar  terminological  difficulties  with  which  psy- 
chology has  had  to  contend  from  the  very  beginning.  Ex- 
pressions denoting  complex  processes,  such  as  idea,  emotion, 
etc.,  become  fixed  in  a language  long  before  those  denoting 
the  simple  processes.  It  was  Wolff,  in  Germany,  who  helped 
to  make  general  the  word  “ Vorstellung”  as  an  equivalent 
of  the  English  word  “idea.”  The  German  word  “Gemiit” 
comes  from  the  original  stem  “mut,”  and  was  used  for  a 
long  time  and  even  by  Kant  as  synonymous  with  “ Seele” 
or  “ Bewusstsein.”  The  mystic  philosophers  gave  it  a dif- 
ferent and  peculiar  meaning  which  we  have  noticed  before.1 
Of  a much  later  date  is  the  differentiation  between  the 
simple  contents  of  consciousness,  which  in  our  modern 
terminology  we  are  accustomed  to  separate  as  sensation  and 
feeling.  From  the  seventeenth  century  onward  the  two 
words  were  used  almost  synonymously.  In  the  philosophy 
of  the  Romantic  period  and  afterward  we  begin  to  note 
an  ambiguity  of  meaning,  for,  on  the  one  hand,  feelings,  as 
the  most  immediately  experienced  subjective  states,  stand 
in  a kind  of  opposition  to  the  peripherally  conditioned 
sensations;  while,  on  the  other  hand,  especially  among  the 
physiologists,  the  feelings  are  restricted  to  certain  kinds  of 
sensation,  e.  g.,  the  sensations  of  the  skin,  the  organic 
sensations,  etc. 

The  principle  of  division  into  simple  and  complex  con- 
tents of  consciousness,  bequeathed  by  John  Locke,  has 
remained  one  of  the  common  characteristics  of  English 
psychology.  And  yet  even  in  England  the  threefold  di- 
vision was  in  a way  retained  by  Lewes,  who  supported  it 
with  a doubtful  analogy  between  the  psychological  spec- 
trum and  the  optical  spectrum.  The  three  principal  colors 

1 Cf.  p.  194. 


204 


HISTORY  OF  PSYCHOLOGY 


led  on  the  psychological  side  to  a threefold  division  into 
sensation,  thought,  and  movement  ( sensation , ycnsee, 
mouvement) , and  the  first  of  these  depended  upon  sensorial, 
the  second  upon  cerebral,  and  the  third  upon  muscle  energy. 
Bain  also  accepted  the  threefold  division  into  thinking, 
feeling,  and  doing.1  But,  alongside  of  this,  he  set  up  the 
more  important  division  of  psychical  phenomena  into 
primitive  and  such  as  developed  out  of  the  primitive.  It 
was  Spencer,  however,  who  was  the  first  to  carry  out  this 
evolutionary  principle  thoroughly.  The  mental  activities 
of  the  developed  consciousness  fall  into  two  groups— cog- 
nitive (memory,  reason)  and  affective  (feeling,  will).  The 
simple  contents  of  consciousness,  which  in  Spencer’s  termi- 
nology are  designated  “feelings,”  can  be  separated  into  emo- 
tions, which  belong  to  the  centre  of  consciousness,  and  into 
sensations,  which  belong  to  the  periphery  of  consciousness. 
This  division  is  supported  by  a second  division,  which,  tak- 
ing an  analytic  point  of  view,  separates  the  feelings  from 
such  parts  of  consciousness  as  can  be  called,  in  general, 
relations  between  feelings.  A “feeling”  represents  any 
part  of  consciousness,  which  is  an  individual  entity  marked 
off  from  the  neighboring  parts  of  consciousness  by  qualita- 
tive differences  and  which  to  introspection  appears  homo- 
geneous. A “relation,”  on  the  other  hand,  is  not  taken  up 
with  any  perceptible  part  of  consciousness.  It  disappears 
at  once  along  with  the  elements  if  one  abstracts  from  these. 
A second  essential  difference  between  these  two  kinds  of 
conscious  experiences  consists  in  the  fact  that  a feeling  of 
relationship  cannot  be  analyzed  into  parts,  whereas  an 
ordinary  feeling  permits  at  least  of  an  imaginary  analysis 
into  similar  parts. 

These  ideas  were  influential  in  forming  the  concept  of 
the  psychical  element,  a concept  which  has  been  decisive 
1 The  Senses  and  the  Intellect,  p.  2. 


THE  CONTENTS  OF  CONSCIOUSNESS 


205 


in  modern  forms  of  classification,  although  even  here  the 
older  principles  in  many  cases  still  exert  their  influence. 

2.  Modern  Forms  of  Classification 

The  differentiation  of  complex  and  simple  contents  of 
consciousness  has  been  decisive  in  different  ways  for  the 
classifications  of  modern  psychology.  Many  attempts 
start  with  the  idea  of  finding  principles  of  opposition  which 
will  be  equally  binding  for  complex  and  for  simple  contents. 
Here  belongs  the  psychology  of  Lipps,  who  set  up  a number 
of  such  principal  oppositions.  The  first  of  these  oppositions 
is  that  between  experiences  of  the  ego  and  conscious  ex- 
periences which  are  not  experiences  of  the  ego;  alongside 
stand  the  no  less  fundamental  oppositions  between  act  and 
receptive  experience,  and  between  act  and  activity.  These 
oppositions,  and  especially  the  first  of  them,  show  a certain 
relationship  to  the  distinction  between  subjective  and 
objective  contents  of  consciousness,  although  this  latter 
division  is  much  more  consciously  dependent  upon  pre- 
suppositions derived  from  the  theory  of  knowledge. 

Husserl  went  back  to  the  researches  of  Brentano  in  regard 
to  intentionality.  By  separating  the  experiences  of  con- 
sciousness into  acts,  i.  e.,  intentional  experiences,  and  not- 
acts, he  arrived  at  a type  of  classification  to  which  the 
fundamental  oppositions  set  up  by  Lipps  would  have  led. 
The  position  to  which  Husserl  relegates  the  feelings  is,  how- 
ever, peculiar.  The  separation  of  all  conscious  experiences 
into  intentional  and  non-intentional  would  be  merely  an 
external  point  of  view  if  experiences  of  the  same  descrip- 
tive genus  showed  at  times  intentional  relation  to  an  object 
and  at  other  times  no  such  relation.  At  the  first  glance 
such  a state  of  affairs  seems  actually  to  exist  in  relation  to 
the  class  ordinarily  called  feelings.  Undoubtedly,  there  are 
intentional  feelings,  e.  g.,  joy  in  a certain  thing.  As  exam- 


206 


HISTORY  OF  PSYCHOLOGY 


pies  of  non-intentional  feelings,  it  is  usual  to  mention  the 
sensational  feelings,  e.  g.,  the  pain  of  a burn  on  the  skin, 
the  pleasurable  taste  of  a certain  food.  The  difficulty  can 
be  solved  by  maintaining  that  these  “feelings”  do  not  be- 
long to  the  same  descriptive  class  as  those  of  pleasure  and 
displeasure.  And,  accordingly,  Husserl  divides  the  totality 
of  feelings  into  affective  sensations  and  affective  acts.  This 
solution  of  the  riddle  of  the  feelings  by  means  of  the  division 
of  experiences  into  sensations  and  acts,  i.  e.,  into  two  dif- 
ferent classes,  is  seen  also  in  other  proposals  for  a method  of 
classification.  We  see  it,  for  example,  in  Stumpf,1  who 
reckons  the  sensational  feelings  as  affective  sensations  and 
classifies  them  along  with  the  sensations. 

Jodi 2 tried  in  a circumspect  manner  to  bring  the  old 
threefold  classification  of  feeling,  willing,  and  thinking 
into  line  with  modern  ideas.  Conscious  activity  is  neither 
cognition  alone  nor  volition  alone  nor  feeling  alone;  it  is 
rather  the  combination  of  the  spontaneity  and  receptivity 
of  an  organic  being.  We  should,  therefore,  no  longer  seek 
for  separate  kinds  of  activities,  for  it  is  rather  the  case  of  a 
single  psychical  activity  appearing  in  various  aspects.  Just 
here  lies  the  chief  difference  of  a classification  in  the  mod- 
ern sense,  in  contrast  to  the  older  standpoint  of  the  fac- 
ulty psychology.  Jodi  finds  in  every  psychological  activity 
three  such  moments — the  impression  from  without  working 
inward;  the  response  from  within  working  outward;  and 
an  inner  connection  between  these  two  links  of  the  chain. 
Thus  result  sense-impressions,  feelings,  and  volitional  ten- 
dencies as  the  three  chief  kinds  of  conscious  reaction  of  or- 
ganic beings  to  the  impressions  of  the  surrounding  world. 

If  we  turn  aside  from  this  attempt  to  find  the  fundamental 
classes  that  are  necessarily  connected  with  conscious  reaction, 

1 “ tJber  Gefuhlsempfmdungen,”  in  Zeitschr.  fiir  Psychologie,  Band 
XLIV,  1907,  p.  1. 

2 Lehrbuch  der  Psychologie,  1896,  p.  130. 


THE  CONTENTS  OF  CONSCIOUSNESS 


207 


there  yet  remains  the  possibility  of  grouping  the  elementary 
contents  from  the  point  of  view  of  our  direct  experience 
of  them.  According  to  this  principle,  Ebbinghaus1  arrived 
also  at  a threefold  division  of  psychical  contents;  but  he 
took  as  the  fundamentally  different  classes  of  experience 
sensations,  images,  and  feelings.  This  point  of  view  of  the 
immediately  perceived  differences  in  the  kinds  of  experience 
would  seem  at  the  first  glance  to  lead  necessarily  to  a per- 
fectly uniform  and  unambiguous  classification.  Strangely 
enough,  however,  it  has  given  rise  to  very  different  ultimate 
classes.  The  fundamental  distinction  between  sensations 
and  their  reproductions  or  images  has  been  questioned,  and 
questioned  by  a classification  that  also  appeals  to  imme- 
diate experience  and  decides  upon  a twofold  classification 
of  the  contents  of  consciousness.  In  Wundt’s  psychology 
sensations  and  feelings  form  the  two  classes  of  elementary 
contents,  a division  which  agrees  with  the  fact  that  imme- 
diate experience  contains  two  factors — an  objective  content 
of  experience  and  the  experiencing  subject. 

In  contradistinction  to  all  other  attempts  at  classifica- 
tion, the  theory  that  there  are  two  principal  kinds  of  ele- 
ments in  consciousness,  the  subjective  and  the  objective, 
rests  upon  the  universal  fact  of  consciousness  that  the 
imaging  subject  can  distinguish  or  differentiate  itself  from 
its  images.  If  this  principle  of  division  is  acknowledged 
there  arise  further  questions  as  to  the  relation  in  which 
these  different  kinds  of  elements  may  stand.  Would  it  be 
conceivable  that  psychological  analysis  should  lead  to  the 
discovery  of  a greater  number  of  elements?  If  we  are  deal- 
ing solely  with  empirically  given  elements,  then  it  must  be 
possible  to  conceive  of  a greater  number  of  elements,  just 
as  it  is  possible  to  conceive  of  a greater  number  of  color 
sensations  than  those  contained  in  the  color  circle.  Such 
1 Grundzuge  der  Psychologie,  I,  1902,  pp.  167  /. 


208 


HISTORY  OF  PSYCHOLOGY 


color  sensations  cannot  be  represented  in  a concrete  ( an - 
schaulich ) manner,  but  they  are  thinkable  exactly  in  the 
same  sense  as  any  abstract  {unanschaulicli ) multiplicity 
is,  e.  g.,  space  in  more  than  three  dimensions.  The  two- 
fold division  of  conscious  experiences  into  subjective  and 
objective  seems  to  be  a perfectly  unique  kind  of  division. 
It  has  often  been  shown  that  sensations  and  feelings  cannot 
as  independent  component  parts  fuse  together  into  one 
whole  called  conscious  experience.  And  the  opposite  opin- 
ions that  those  classes  are  nothing  else  than  characteristics 
or  different  sides  of  the  same  conscious  experience,  leads 
into  great  difficulties  in  facing  the  problem  of  making  clear 
this  union  of  the  subjective  and  objective  sides  of  conscious- 
ness. As  an  analogy  the  union  of  the  intensity  and  quality 
of  a tone  might  be  made  use  of.  But  these  two  character- 
istics have  a bearer,  or  substratum,  namely,  the  tone. 
Whether  consciousness  could  be  in  this  sense  considered 
the  substratum  of  feeling  and  sensation  remains  yet  to  be 
settled.  Possibly  the  combination  which  the  elements  of 
consciousness  form  together  is  just  as  inconceivable  (un- 
anschaulich)  as  the  combination  of  a real  and  imaginary 
number  into  one  complex  number,  a bi. 

The  discussion  of  this  position  throws  a new  light  upon 
those  attempts  which  aimed  at  finding  one  single  class  of 
psychical  elements.  This  they  achieved  in  considering  sen- 
sations as  the  most  readily  isolated  component  parts  of 
conscious  life.  The  historical  background  of  this  line  of 
thought  is  formed  by  the  intellectualism  of  Herbart,  who 
recognized  only  simple  ideas  and  identified  these  abso- 
lutely with  sensations.  In  recent  years  Miinsterberg1  has 
modified  this  theory  in  a surprising  manner.  He  starts 
out  from  the  standpoint  of  method,  from  the  possibility  of 
the  communication  of  psychical  contents.  The  two  com- 
1 Grundzuge  der  Psychologie,  I,  1900,  p.  309. 


THE  CONTENTS  OF  CONSCIOUSNESS 


209 


munications  that  it  is  raining  outside  and  that  I am 
happy  are  from  the  point  of  view  of  method  absolutely 
distinct.  The  first  case  of  outer  sense-impression  can  be 
explained  by  direct  description  of  the  content  of  conscious- 
ness; but  in  regard  to  the  latter  I can  never  really  tell  if 
that  which  the  other  calls  a feeling  of  joy  may  not  be  what 
I call  anger.  Psychology  has  therefore  to  resort  to  indirect 
description,  and  it  does  this  by  considering  the  total  content 
of  consciousness  as  a combination  of  elements  which  in  the 
images  of  sense-impressions  show  noetical  relations  to  the 
physical  world.  Such  elements  are,  however,  nothing  else 
than  sensations.  If  two  sensations  are  similar  to  each  other 
we  are  driven  to  the  conclusion  that  each  of  them  is  divided 
into  parts,  some  of  which  are  common  to  them  both.  Now, 
since  each  sensation  shows  some  similarity  with  some  other 
and  is  never  unique,  it  therefore  follows  that  no  sensa- 
tion represents  a psychological  atom  and  that  each  is  com- 
posed of  elementary  component  parts.  These  thoughts 
lead  to  an  atomic  theory  of  consciousness  which  goes  far 
beyond  the  claim  of  sensation  to  be  recognized  as  a psychi- 
cal element  which  is  not  further  divisible.  They  lead  us 
to  seek  the  true  elements  of  psychical  life  beyond  sensation. 
Of  course,  Miinsterberg  cannot  maintain  that  psychical 
processes  are  in  absolute  reality  nothing  but  sensations; 
he  admits  they  are  unities,  but  in  our  analysis  of  them  we 
may  arrange  them  in  some  new  form.  Thus  an  image  is 
made  up  of  elements  in  the  sense  that  there  is  a special 
logical  value  in  the  notion  of  an  image  as  being  a combina- 
tion of  elements. 

All  these  modern  forms  of  classification  have  started  with 
the  principle  of  analysis,  and  they  have  ended  logically  in 
the  problem  of  the  psychical  element,  and,  as  we  have  seen, 
this  element  has  changed  its  role  very  often  in  the  classifi- 
cations we  have  described. 


210 


HISTORY  OF  PSYCHOLOGY 


3.  The  Concept  of  the  Psychical  Element 

The  demands  which  led  to  the  modern  concept  of  the 
psychical  element  are  in  direct  opposition  both  to  the  tra- 
ditional faculty  psychology  and  to  the  more  recent  conten- 
tion that  a simple  content  of  consciousness,  as,  for  example, 
the  simple  idea  of  Herbart,  can  exist  in  and  for  itself.  Much 
rather  are  we  to  conceive  of  the  parts  of  our  continuous 
psychical  experience  as  incessantly  entering  into  all  kinds 
of  relations  with  one  another.  The  elements,  however, 
are  what  he  beneath  theses  They  cannot  be  further  ana- 
lyzed, although  they  may  appear  in  any  combination. 

In  this  manner  Wundt  established  the  concept  of  the 
psychical  element.  In  opposition  to  this,  however,  the  de- 
scription of  consciousness  as  “a  stream  of  thought”  was 
used.  According  to  Dilthey1  this  continuous  flow  of  the 
contents  of  consciousness  forms  an  impediment  to  the  use 
of  any  kind  of  “element”  concept.  A slight  change  in  the 
concept  is  brought  about  when  the  elements  are  looked  upon 
as  mere  artifices  for  the  purposes  of  abstraction,  and  in  this 
form  the  concept  has  been  made  the  foundation  of  many 
popular  presentations  of  psychology,  as,  for  example,  in 
the  psychology  of  Rehnike.'2  In  the  controversy  over  this 
concept  an  analogy  between  the  physical  and  psychical 
atoms  was  often  made  use  of,  but  this  analogy  fails  precisely 
in  the  most  important  point.3  The  psychological  elemen- 
tary concepts  ought  not  to  be  compared  with  the  analysis 
of  matter  into  atoms,  but  rather  with  the  analysis  of 
a movement  into  its  components  or  into  the  momentary 
velocities  of  a moving  point.  These  are  the  only  things 

1 “Ideen  uber  eine  beschreibende  und  zergliedemde  Psychologie,”  in 
Sitzungsbericht  d.  Berl.  Akad.,  Xo.  53,  1S94. 

2 J.  Rehnike,  ATlgemeine  Psychologie,  1904. 

3 Cf.  Wundt,  Grundz.  d.  physiolog.  Psychol.,  I (6  Aufl.),  190S,  p.  417. 


THE  CONTENTS  OF  CONSCIOUSNESS 


211 


that  would  at  all  correspond  in  the  department  of  physics. 
The  continual  change  of  conscious  experiences  hinders  the 
determination  of  psychical  elements  just  as  little  as  a ve- 
locity changing  from  point  to  point  hinders  the  determina- 
tion of  the  momentary  velocity  at  any  single  one  of  these 
points. 

The  question  as  to  the  kind  and  number  of  such  elements 
becomes,  then,  a purely  empirical  one.  Taking  this  position, 
psychology  cuts  itself  completely  loose  from  all  the  entice- 
ments of  a metaphysic  of  consciousness,  which  sees  in  the 
classes  of  the  content  of  consciousness  the  expression  of 
ideal  regularity  according  to  law.  This  question  of  the 
psychical  elements  is  not  merely  a question  of  a new  group- 
ing of  long-known  contents  of  consciousness.  In  recent 
years  we  have  seen  how  systematic  introspection  has  led  to 
the  discovery  of  a class  of  experiences  up  till  now  totally 
disregarded,  the  so-called  states  of  awareness,1  which,  ac- 
cording to  the  opinion  of  Ach,  must  be  considered  as  an  inde- 
pendent class  along  with  the  previously  recognized  classes. 
This  explains,  in  a way,  the  difference  of  opinion  which  at 
present  exists  as  to  the  number  and  nature  of  the  psychical 
elements.  Even  though  attempts  at  classification  can  be 
traced  back  to  the  oldest  period  of  psychological  thought, 
yet  the  problem  of  the  psychical  element  implicit  in  them  is 
the  product  of  the  last  few  years. 

1Cf.  pp.  136/. 


CHAPTER  VIII 


PSYCHOLOGICAL  METHODS 

In  the  development  of  psychological  methods,  as  in  the 
development  of  the  methods  of  any  science,  we  can  divide 
the  methods  into  two  kinds : those  that  procure  a knowledge 
of  the  facts,  i.  e.,  the  practical  or  working  methods,  and  those 
that  serve  to  work  up  special  facts,  i.  e.,  the  theoretical 
methods.  Scarcely  any  other  science  has  had  those  of  the 
first  kind  ever  questioned,  but  psychology  has  had  to  fight 
for  their  recognition.  In  the  controversies  as  to  the  rela- 
tion between  introspection  and  observation,  theoretical 
view-points  have  mostly  predominated.  And  the  same  is 
true  of  the  attempts  that  arose  from  this;  namely,  to  base 
psychology  upon  physiology.  It  was  only  the  development 
of  psychical  methods  of  measurement  that  led  to  real 
working  methods,  which  had  as  their  aim  exact  and,  as  far 
as  possible,  quantitative  results. 

i.  Observation  and  Introspection 

That  psychological  facts  are  given  only  to  our  inner 
experience  can  never  be  seriously  questioned.  And  there 
are  many  psychologists  of  the  present  day  who  are  of  the 
opinion  that  introspection  alone  is  perfectly  sufficient  to 
obtain  a knowledge  of  them.  Scientific  introspection  is, 
of  course,  considered  to  be  a special  art,  which  is  more 
full  of  content  and  more  systematic  than  common  intro- 
spection. The  apparatus  it  makes  use  of  is  no  other  than 

212 


PSYCHOLOGICAL  METHODS  213 

/ 

that  which  always  stands  and  has  always  stood  within  the 
reach  of  every  man.  It  becomes  more  and  more  refined  in 
proportion  as  the  conscious  life  itself  becomes  richer  and  more 
varied,  but  a real  history  of  these  methods  can  scarcely 
be  said  to  exist. 

It  is  possible  that  the  irregular  course  of  the  history  of 
psychology,  interrupted  by  so  many  leaps  and  bounds,  may 
have  something  to  do  with  this  peculiarity  of  introspection. 
The  continuity  of  psychological  thought  has  often  been 
broken.  How  often  a pre-Raphaelite  return  to  long-for- 
gotten forms  of  thought  has  followed  a period  of  the  keenest 
hopes  and  anticipations!  Is  not  the  fact  that  each  single 
individual,  by  means  of  his  introspections,  has  access  to  all 
psychical  phenomena  a temptation  and  an  urgent  motive 
to  begin  all  over  again  from  the  very  first?  Certainly  the 
theory  of  the  inner  sense,  which  arises  in  a certain  historical 
relation  with  introspection,  busied  itself  with  the  peculiar- 
ities of  introspection.  But  this  did  not  result  in  a develop- 
ment of  the  achievements  of  introspection,  but  only,  on 
the  one  hand,  in  a kind  of  hinting  in  a fantastic  way  at  such 
possibilities,  and,  on  the  other  hand,  in  drawing  a distinc- 
tion between  the  methods  of  introspection  and  those  of  the 
so-called  outer  observation. 

Even  though  we  may  acknowledge  that  introspection 
is  the  presupposition  of  every  psychology,  nevertheless 
introspection  was  by  no  means  the  beginning  of  scientific 
psychology.  It  is  through  nature  that  man  has  not  only 
got  to  know  himself  but  has  also  learned  to  observe  himself.1 
It  is  no  mere  chance  that  the  first  psychological  knowledge 
among  the  Greeks  comes  from  mathematicians  and  physi- 
cists. Of  course  it  is  true  that  many  universally  valid  facts 
of  human  psychical  life  appear  also  in  mythological  ideas 
and  in  the  concrete  expressions  of  such  in  art.  But  it 

1 Cf.  H.  Ebbinghaus,  Kultur  der  Gegenwart,  I,  6,  1908,  pp.  175  ff. 


214 


HISTORY  OF  PSYCHOLOGY 


was  first  of  all  the  methods  which  had  been  used  in  the 
scientific  research  of  outer  phenomena  that  led  to  a theo- 
retical psychology,  the  first  outlines  of  which  Plato,  the 
founder  of  logic  and  ethics,  formulated,  at  least  for  thought 
and  volition. 

This  same  connection  can  also  be  seen  in  the  important 
influence  that  the  example  of  the  methods  of  natural  science 
has  had  upon  the  formation  of  modern  psychology.  Even 
before  practical  psychological  methods  were  formed  in 
analogy  to  the  latter,  the  idea  of  strict  and  universal  reg- 
ularity in  mental  phenomena  was  recognized.  The  great 
metaphysicians  of  the  seventeenth  century,  Spinoza  and 
Leibniz,  were  convinced  that  mental  phenomena  agreed 
with  the  phenomena  of  outer  nature  in  regard  to  the  strict 
regularity  of  their  course.  The  association  psychology 
must  be  given  credit  for  having  turned  this  belief  to  ac- 
count by  formulating  certain  psychological  concepts  which 
were  of  great  help  for  empirical  psychology.  Hobbes  ex- 
plained the  strict  regularity  of  our  thought  processes  by 
means  of  the  continuance  of  material  movements  in  the 
brain  and  thereby  created  in  the  mental  sphere  an  analogy 
to  the  physical  principle  of  inertia.  A century  later  Newton 
introduced  into  physics  the  idea  of  attracting  forces,  and 
then  we  find  in  the  psychology  of  Hume  also  a kind  of  at- 
traction of  ideas.  Inertia  and  attraction  were  able  to  ex- 
plain the  mechanical  principles  of  the  outer  world.  Founded 
on  analogies  with  these,  the  concept  of  association  in  the 
mental  sphere  seemed  to  be  designed  to  do  the  same  for 
mental  phenomena.  Last  of  all  we  have  Herbart,  who  went 
furthest  with  these  mechanical  analogies.  Filled  with  the 
conviction  that  the  regularity  of  mental  life  was  similar 
to  that  of  the  heavens,  he  provided  his  ideas  with  all  the 
characteristics  of  elastic  bodies,  which,  enclosed  within  a 
narrow  space,  exerted  pressure  upon  each  other. 


PSYCHOLOGICAL  METHODS 


215 


In  spite  of  all  this,  such  analogies  left  a great  deal  of  room 
free  for  the  building  up  of  psychology  itself.  But,  in  more 
recent  developments  of  the  science,  this  was  in  danger  of 
being  limited  by  a direct  transference  of  the  methods  of 
natural  science  to  psychology,  and  this  transference  led  so 
far  as  to  give  rise  to  the  demand  that  psychology  must 
be  methodically  based  upon  physiology. 

2.  Physiology  the  Basis  of  Psychology 

The  influences  of  the  natural  sciences  upon  the  methods 
of  psychology  are  certainly  not  the  only  ones  under  which 
the  latter  have  come,  for  the  differences  in  method  have 
certainly  not  been  less  than  the  differences  in  the  general 
trend  of  psychology.  And  yet  these  influences  have  been 
of  the  greatest  importance  for  our  science  at  the  pres- 
ent day. 

The  opportunity  for  a direct  attack  by  the  natural  sciences 
was  given  when  the  question  as  to  the  relation  between 
observation  and  introspection  had  been  decided  in  the  sense 
that  the  latter  could  never  become  a scientific  method. 
Out  of  this  arose  the  demand  to  seek  the  methodical  basis 
of  the  science  of  the  soul  in  another  department  of  science, 
and  the  most  natural  department  was,  of  course,  brain  phys- 
iology. Comte’s  protest  against  introspection1  lost  much 
in  force  because  of  his  questionable  suggestion  that  psy- 
chology should  be  based  upon  phrenology  as  Gall  had  de- 
fined the  latter.  In  contradistinction  to  this,  Maudsley 
demanded  that  psychology  be  theoretically  based  upon 
physiology.  In  a criticism  of  J.  S.  Mill’s  work  on  Hamilton 
he  proposed  with  great  determination  to  substitute  a purely 
physiological  method  in  place  of  the  method  of  introspec- 
tion to  which  Mill  had  assented.2  In  his  chief  work,  The 

1 Cf.  p.  154. 

2 This  criticism  appeared  in  The  Journal  of  Mental  Science,  1866. 


216 


HISTORY  OF  PSYCHOLOGY 


Physiology  and  Pathology  of  the  Soul,  he  contended  that  it 
was  impossible  to  attain  any  results  by  the  old  method; 
such  an  undertaking,  he  says,  is  just  as  hopeless  as  trying 
to  illuminate  the  universe  with  one  tallow  candle.  Mauds- 
ley  supported  his  contentions  partly  by  means  of  the  cur- 
rent arguments  of  materialism.  Material  conditions  are  at 
the  bottom  of  all  psychical  life,  and,  naturally,  physiology 
is  best  able  to  give  an  account  of  these.  The  organic  metab- 
olism of  the  brain  is  always  influencing  consciousness; 
nothing  is,  therefore,  more  certain  than  that  psychical 
phenomena  are  dependent  upon  physiological  conditions. 
More  important,  however,  are  the  peculiar  but  purely 
psychological  reasons  that  Maudsley  brings  forward.  Since 
conscious  life  is  not  a continuous  activity,  consciousness 
cannot  give  sufficient  information  about  the  static  states  of 
the  soul.  Only  physiology  can  teach  us  about  the  inactive 
state  of  the  soul,  which  is  not  accompanied  by  consciousness. 
But  even  of  the  activities  of  the  soul  themselves,  the  most 
important  take  place  without  consciousness.  This  last  ar- 
gument involves  itself  at  best  in  a contradiction,  since  the 
hypothesis  of  unconscious  psychical  processes  presupposes 
a certain  amount  of  purely  psychological  knowledge. 

A similar  attempt  was  made  in  Germany  on  the  part  of 
Horwicz,  which  tried  to  avoid  such  contradictions.  After 
more  or  less  lengthy  discussions  as  to  method,1  he  admitted 
in  his  Psychologische  Analysen  auf  physiologischer  Grund- 
lage  (1872  to  1878)  the  necessity  for  a kind  of  introspection, 
but  only  for  the  sake  of  a preliminary  orientation  of  the  total 
mass  of  psychic  activities.  But  it  is  the  physiology  of  the 
bodily  organism  which  is  the  real  foundation,  for  the  organ- 
ization of  the  soul  corresponds  to  the  organization  of  the  body. 
It  is  by  the  physiological  method  that  the  scientist  arrives 
at  a division  of  psychical  phenomena;  and  so  in  the  same 
1 Zeitschr.  f.  Philos,  u.  philos.  Krit.,  Bd.  LX,  1872,  p.  170. 


PSYCHOLOGICAL  METHODS 


217 


way  should  he  determine  the  number  and  the  characteris- 
tics of  the  mental  elements  and  the  laws  of  their  combina- 
tion. This  important  support  that  the  physiological  method 
was  promising  psychology  has  an  analogy  in  the  relation- 
ship between  some  other  sciences,  all  of  which  can  be  traced 
back  to  the  influence  of  Comte’s  classification  of  the  sciences, 
where  each  one  served  as  handmaid  to  a superior  science, 
and  where  all  were  arranged  in  an  ascending  series  from  the 
least  important  to  the  most  important.  In  this  scale,  psy- 
chology is  related  to  physiology  as  physics  to  mathematics 
or  as  geography  to  astronomy.  Against  all  this  it  has  been 
objected  that  even  if  physical  and  psychical  phenomena 
were  still  more  closely  connected,  the  absolute  hetero- 
geneity of  the  two  kinds  of  phenomena  would  make  every 
conclusion  carried  over  from  the  one  department  to  the 
other  merely  an  analogy.  And,  in  fact,  the  psychology  of 
Horwicz  is  built  upon  the  insecure  foundation  of  analogies. 
The  chief  part  is  played  by  the  concept  of  assimilation  in 
the  physiological  and  in  the  psychological  sense;  a further 
analogy  exists  between  the  opposition  of  sensory  and  motor 
nervous  activities  on  the  one  hand  and  the  general  division 
of  our  total  psychical  life  into  theoretical  and  practical 
activities  on  the  other.  Upon  this  Horwicz  builds  a divi- 
sion of  psychical  phenomena  which  in  the  main  agrees  with 
that  “really  perfectly  correct  skeleton  of  mental  life  which 
was  set  up  by  Wolff.”  That  such  conclusions  drawn  from 
analogies  could  become  a proof  of  or,  worse  still,  a substi- 
tute for  a psychologically  determined  division  merely  goes 
to  show  to  how  great  a degree  Horwicz  had  lost  sight  of  the 
aims  of  psychology  in  his  great  admiration  for  the  successes 
in  the  field  of  physiology. 

In  quite  a different  sense  did  the  physiological  method 
become  an  aid  to  psychology  in  the  physiological  psychology 
of  Wundt.  That  this  is  in  the  first  instance  psychology 


218 


HISTORY  OF  PSYCHOLOGY 


and  that  it  attempts  to  investigate  the  processes  of  con- 
sciousness in  the  combinations  they  form  among  them- 
selves— all  this  follows  from  Wundt’s  definition  of  psychology 
which  was  quoted  above.1  Physiological  psychology  at- 
tempts to  deduce  the  psychical  from  the  physical  phe- 
nomena of  life  just  as  little  as,  for  example,  microscopical 
anatomy  might  attempt  to  give  an  explanation  of  the  ca- 
pacities of  the  microscope  from  the  facts  of  anatomy.  Physi- 
ology is  drawn  upon  partly  for  supplementary  purposes,  as, 
for  example,  in  questions  as  to  the  physical  basis  of  mental 
life,  but  this  latter  is  not  bounded  by  these  facts  but  leads 
right  on  to  the  other  problems  of  psychology  that  border 
upon  philosophy.  But  partly  and  chiefly  do  we  mean  by 
physiological  psychology  the  incorporation  of  the  exper- 
imental methods  developed  by  physiology.  Of  these  ex- 
perimental methods  in  the  broadest  sense  the  most  important 
part  has  been  played  by  the  methods  of  psychical  measure- 
ment, which  from  the  very  beginning  centred  around  the 
problem  of  a psychical  scale. 

3.  The  Development  of  the  Methods  of  Psychical 
Measurement 

Nowhere  do  we  see  more  clearly  than  in  the  development 
of  the  methods  of  psychical  measurement  what  an  influence 
upon  the  development  of  a method  its  subordination*  to  some 
theoretical  point  of  view  may  exert  even  though  the  latter 
may  in  later  years  have  to  be  sacrificed.  It  is  certain  that 
there  is  not  one  of  the  methods  of  psychical  measurement 
that  did  not  exist  in  its  broad  outlines  before  the  time  of 
Fechner.  Yet  it  was  only  through  him  that  these  methods 
became  a recognized  part  of  experimental  psychology.  Even 
the  concept  of  the  psychical  measure  is  much  older  than 

1 See  p.  162. 


PSYCHOLOGICAL  METHODS 


219 


the  psychophysics  of  Fechner.1  And  yet  it  was  Fechner 
who  was  the  first  to  bring  the  experimental  methods  into 
relationship  with  the  problem  of  a psychical  measure  and 
in  this  way  lead  to  a theoretical  discussion  of  these  methods. 
Not  the  discovery  of  a new  method  of  procedure  but  merely 
a change  in  the  point  of  view  led  to  the  rise  of  the  methods 
of  psychical  measurement. 

The  common  starting-point  of  all  these  methods  lies  in 
those  methods  which  are  used  to  determine  the  size  of 
physical  quantities.  Everywhere  where  the  inaccuracy  of 
sense-impressions  led  to  unavoidable  mistakes  in  observa- 
tion, there  arose  the  necessity  of  approximating  to  the 
objective  values  as  nearly  as  possible  by  means  of  increas- 
ing the  number  of  observations.  The  systematic  applica- 
tion of  these  methods  of  eliminating  error  to  the  problem 
of  the  determination  of  psychical  measurement  was  left  for 
Fechner  to  take  up  in  his  psychophysics.  The  classifica- 
tion and  the  names  that  Fechner  gave  to  these  methods  of 
measurement  have  been  repeatedly  modified  according  to 
the  peculiarities  of  the  methods  that  have  appeared  most 
characteristic.  For  example,  Ebbinghaus  divides  the  meth- 
ods into  those  of  stimulus  determination  and  those  of  judg- 
ment determination;  G.  E.  Muller  into  the  methods  of  con- 
stant changes  and  of  limits;  and  Wundt,  who  kept  longest 
to  Fechner’s  division,  recently  divided  them  into  gradation 
and  enumeration  methods. 

In  the  development  of  the  methods  there  has  been  a 
gradual  differentiation  between  those  two  chief  groups, 
which  became  clear  according  to  the  problems  allotted  to 
them  by  Fechner.  Now,  according  to  Fechner,  all  methods 
exist  for  the  purpose  of  bringing  into  relation  definite  parts 
of  the  scale  of  sensation  with  definite  parts  of  the  stimulus 
scale,  so  as  to  be  able  to  measure  sensation  by  some  unit. 

1 See  below,  Chapter  IX. 


220 


HISTORY  OF  PSYCHOLOGY 


In  calling  these  methods  of  measurement  “psychophysical,” 
Fechner  hints  at  the  fundamental  duty  of  psychophysics. 
The  just-noticeable  difference  was  taken  to  represent  the 
unit  of  sensation.  The  methods  could  either  find  these 
units  directly  or  arrive  at  them  by  calculation.  The 
methods  of  the  first  kind,  which  because  of  their  more 
natural  procedure  are  in  general  the  older,  can  be  called 
the  gradation  methods  ( Abstufungsmethoden ).  In  contra- 
distinction to  these  the  methods  of  the  second  class  were 
grouped  together  under  the  name  of  the  “error”  methods, 
a name  which  is  not  at  all  happy  in  describing  the  difference 
between  the  two  classes.  For  every  method  has  to  reckon 
with  unavoidable  errors  of  observation  and  becomes  in  its 
exact  manipulation  an  error  method.  And,  in  fact,  the  old 
experiments  which  attempted  to  find  directly  the  just-no- 
ticeable difference  have  been  mostly  worked  over  again  in 
new  ways  under  the  influence  of  the  discussions  arising  out 
of  the  theory  of  error. 

(a)  The  Older  Forms  of  the  Methods 

Ernst  Heinrich  Weber  came  upon  his  most  important 
discoveries  in  the  sphere  of  psychical  measurement  with  the 
help  of  the  simplest  and  most  natural  of  methods.  He 
tried  to  find  directly  the  least  stimulus  difference  that  could 
just  be  noticed.  Since  it  was  by  experiments  of  this  kind 
that  Weber  proved  the  law  that  bears  his  name,  the  method 
of  least  differences  held  for  a long  time  the  first  place.  As 
so  often  happens  with  investigators,  who  see  for  the  first 
time  in  broad  outline  a new  field  of  science,  Weber  an- 
ticipated or  pointed  the  way  to  almost  all  the  methods  of 
psychical  measurement  that  were  later  developed.  When 
in  determining  the  sensitivity  of  the  sense  of  touch  he  placed 
weights  simultaneously  on  the  finger  and  the  forearm, 


PSYCHOLOGICAL  METHODS 


221 


whereupon  the  weight  on  the  forearm  appeared  lighter,  he 
was  working  according  to  what  became  later  known  as  the 
method  of  equivalents.1  He  also  let  the  same  weights,  which 
were  in  the  ratio  39 : 40,  be  lifted  many  times,  and  main- 
tained, on  the  ground  of  the  frequency  of  the  right  judg- 
ments, that  the  majority  of  people  would  be  able  to  dis- 
tinguish by  means  of  muscle-sensations  two  such  weights 
without  a previous  long  period  of  practice;  in  this  he  an- 
ticipated the  method  of  right  and  wrong  cases.2 

The  method  used  with  such  success  by  Weber  was  called 
by  Fechner  the  method  of  just-noticeable  differences  and 
ranked  first  among  the  methods  for  measuring  difference 
sensitivity.3  In  its  use,  for  example,  in  investigating  the 
fineness  with  which  differences  of  weight  can  be  distin- 
guished, the  method  consists  in  determining  the  extent  of 
the  difference  in  the  weight  that  is  necessary  in  order  to  be 
just-noticeably  perceived.  Fechner  saw  the  chief  advan- 
tage of  this  method  in  the  fact  that  the  just-noticeable 
difference  could  be  immediately  perceived  as  the  same  for 
the  sensation.  The  extent  of  the  just-noticeable  difference 
certainly  leaves  some  free  play  to  the  subjective  judgment, 
even  though  one  may,  so  to  say,  come  to  some  agreement 
with  oneself  as  to  the  feeling  of  a small  and  just-sufficiently 
sensed  difference  and  be  able  to  reproduce  this  with  sufficient 
accuracy  in  different  tests.  Now,  although  Fechner  calls 
this  method  the  most  important  tool  of  psychophysics,  yet 
it  is  clear  that  he  felt  that  its  results  are  really  of  a prelim- 
inary nature,  and  that  a real  decision  can  be  reached  only 
by  those  methods  that  are  founded  upon  the  principles  of 
the  theory  of  error. 

Alongside  of  the  method  of  just-noticeable  differences 
has  often  been  placed  the  method  of  mean  gradations.  The 

1 Tastsinn  und  Gemeingefuhl,  p.  548.  2 Cf.  p.  128. 

3 Elemente  der  Psychophysik,  I,  1860,  pp.  71  ff. 


222 


HISTORY  OF  PSYCHOLOGY 


chief  idea  of  this  method  is  to  determine  equally  large  differ- 
ences of  sensation  by  immediate  judgment.  In  this  way  this 
method  forms  a natural  continuation  of  the  problem  as  for- 
mulated by  Fechner  for  the  methods  of  measurement.  In- 
stead of  taking  the  roundabout  way  of  just-noticeable  differ- 
ences, it  appeared  much  more  profitable  to  investigate  the 
relations  between  the  systems  of  stimulus  and  sensation  by 
means  of  judging  more  than  noticeable  differences.  Plateau1 
had  been  the  first  to  use  for  psychical  measurements  in  this 
sense  the  possibility  of  determining  a sensation  midway 
between  a stronger  and  a weaker  one  with  a fair  degree  of 
certainty.  He  asked  eight  persons  who  had  had  practice 
in  painting  to  determine  a gray  midway  between  a pure 
white  and  a deep  black,  and  he  found  the  result  to  be  almost 
identical  with  all  of  them.  We  cannot  here  go  further  into 
the  numerous  modifications  of  these  methods,  as,  for  ex- 
ample, the  method  of  double  stimuli  introduced  by  Merkel2 
whereby  a stimulus  is  to  be  found  that  gives  twice  as  strong 
a sensation  as  a given  stimulus.  The  theoretical  importance 
of  such  a mean  sensation  is  determined  by  one’s  general 
opinions  of  psychical  measurement. 

(b)  The  Influence  of  the  Theory  of  Error 

After  the  method  of  just-noticeable  differences  Fechner 
ranks  the  method  of  right  and  wrong  cases  and  the  method 
of  average  error.  The  two  latter  attempt  to  determine 
the  relation  between  the  immediate  results  of  observation 
and  the  values  sought  by  psychical  measurement  on  the 
basis  of  the  theory  of  error.  In  the  determination  of  ab- 
solute sensitivity  the  method  of  mean  gradations  goes  over 
into  the  method  of  equivalents,  where  the  observer  has  to 

1 Bulletins  de  Vacademie  royale  de  Belgique,  t.  XXXIII,  1872,  p.  376.' 

2 Phil.  Stud.,  Bd.  IV,  1888,  p.  545. 


PSYCHOLOGICAL  METHODS 


223 


choose  a stimulus  that  appears  the  same  as  a given  one, 
other  things  being  equal  ( e . g.,  on  a different  part  of  the 
skin).  In  using  the  method  of  average  error  the  observer 
has  to  arrange  two  stimuli  so  that  they  shall  be  equal;  the 
average  error  made  in  doing  this  is  brought  into  relation  with 
the  difference-threshold.  The  method  of  right  and  wrong 
cases  calls  for  numerous  judgments  upon  one  and  the  same 
stimulus  lying  near  to  the  difference-threshold.  Rather 
hypothetical  discussions  in  the  theory  of  error  are  required 
in  order  to  come  to  any  definite  conclusions  as  to  the  nature 

of  the  difference-threshold  from  the  relation  | ^ j between 

the  number  of  right  cases  (r)  and  the  total  number  of  cases 
(■ n ),  which  results  from  employing  this  method. 

In  these  methods  also  Fechner  was  not  without  prede- 
cessors. Especially  in  photometrical  determinations  had 
the  importance  of  the  average  error  been  previously  shown. 
Steinheil1  had  considered  the  average  error,  which  was  made 
in  arranging  two  similarly  bright  fields  in  the  prism  pho- 
tometer, as  a measure  for  the  possibility  of  differentiation  of 
two  brightnesses.  And  the  method  of  right  and  wrong  cases 
had  been  used  in  experiments  as  to  the  possibility  of  deter- 
mining the  differences  of  tone  intensity,  which  had  been 
carried  out  by  Renz  and  Wolf  under  Vierordt’s  direction.2 

The  theoretical  discussion,  however,  first  arose  because 
Fechner  treated  these  methods  according  to  the  principles 
of  the  theory  of  error.  In  order  to  be  able  to  draw  definite 
conclusions  from  the  size  of  the  average  error  as  regards  the 
certainty  of  the  observation,  a knowledge  of  the  distribu- 
tion of  the  errors  or  of  the  law  of  error  is  necessary.  The 
first  attempts  to  arrive  at  the  true  value  of  a quantity  from 

1 Elemente  der  Helligkeitsmessungen  am  Stemenhimmel,  1837.  Cf. 
below,  Chapter  IX,  1 (6). 

2 Vierordt’s  Archiv,  1856,  Heft  2,  p.  185. 


224 


HISTORY  OF  PSYCHOLOGY 


quantities  that  contain  errors  of  observation  are  met  with 
in  the  eighteenth  century.1  Roger  Cotes  (1722),  in  an  investi- 
gation of  the  errors  of  values  obtained  in  observation,  com- 
pared the  errors  to  weights  of  reciprocal  value,  which  are  to 
be  added  on  to  the  separate  points;  the  centre  of  gravity  of 
such  a system  coincides  then  with  the  true  value.  The  im- 
portance of  the  arithmetical  mean  of  a series  of  observations 
of  the  same  objective  quantity  was  first  recognized  by 
Thomas  Simpson  in  1757.  He  showed  also  how  the  relia- 
bility of  such  a mean  value  increased  with  the  increase  of 
the  observations.  Lambert,  in  1760,  reached  more  accurate 
conclusions  in  his  photometrical  investigations.  If  negative 
and  positive  errors  appear  equally  often,  and  if,  further,  the 
supposition  is  valid  that  large  errors  occur  less  often  than 
small  ones,  then  the  arithmetical  mean  is  the  truest  value. 
In  Lambert’s  Theorie  der  Zuverldssigkeit  der  Beobachtungen 
und  Versuche  there  are  fairly  arbitrary  presuppositions  as  to 
the  calculation  of  the  mean. 

A test  of  the  method  of  finding  the  mean  by  the  more 
accurate  help  of  the  theory  of  probability  is  first  found  in 
Lagrange.2  Daniel  Bernoulli,  in  a publication  of  the  Saint 
Petersburg  Academy  on  the  compensation  of  errors  of  obser- 
vation (1778),  tried  to  supply  the  want  of  a special  form  for 
the  law  of  the  distribution  of  error.  For  the  probability 
(; y ) of  an  error  (A)  Bernoulli  established  the  equation: 


If  we  imagine  the  separate  values  A arranged  along  an 
abscissa,  then  the  probability  curve  is  a semicircle  with  the 
radius  r and  the  centre  A = 0.  If  a,  b,  c . . . are  the  ob- 
served values  and  x the  most  probable  value,  then  the  er- 

1 Cf.  the  sketch  of  the  history  of  the  theory  of  error  in  G.  F.  Lipps, 
Die  psychischen  Massmethoden,  1906,  pp.  33  ff. 

2 Miscellania  Taurinensia,  Bd.  V,  1770-1773. 


PSYCHOLOGICAL  METHODS 


225 


rors  of  observation  (A)  are  represented  by  the  differences 
a — x,  b — x,  c — x.  . . . The  value  x itself  is  deter- 
mined by  the  condition  that  the  product 

-\J  r1—  (x  — a)2  . -\J r2—(x  — b)2  . -yj  r2  — (x  — c)2 

be  a maximum.  With  this  Bernoulli  had  given  a formal  so- 
lution of  the  problem,  but  his  law  of  error  took  for  granted 
the  same  finite  field  of  error  for  all  series  of  observations. 
It  was  impossible  by  means  of  it  to  do  justice  to  the  dif- 
ferences in  the  certainty  of  observations,  which  are  seen 
in  various  distributions  of  the  errors  as  when  they  crowd 
around  the  middle  value  or  are  scattered  over  a larger  area. 

A strictly  valid  theory  of  error  was  first  obtained  by 
Gauss.1  Assuming  that  by  repeated  immediate  observations 
of  a quantity  the  arithmetical  mean  of  all  the  observations 
is  the  most  probable  value,  he  deduced  for  the  probability 
( y ) of  an  error  (A)  the  famous  formula 

h A 

y— — -e-ft2A2. 
y'  7 r 

where  the  parameter  h gives  a measure  for  the  accuracy  of 
the  observations.  If,  again,  the  observed  values  are  denoted 
by  a,  b,  c,  . . . and  the  most  probable  value  by  x,  then  in 
this  case  the  product 

h h h 

g-hKa-x )2  . g-ft!(6-z)2  . g-hKc-x)*  # , . 

V 7T  1/  7T  V 7T 

must  be  a maximum.  And  this  is  the  case  if  the  sum  of 
(o— x)2+  (b— x)2+  (c— x)2  . . . 

be  a minimum.  And  with  this  Gauss  arrived  again  at  the 
method  of  least  squares,  which  he  had  used  since  1795,  and 
1 Theoria  motus  corporum  ccdestium,  1809. 


226 


HISTORY  OF  PSYCHOLOGY 


in  regard  to  which  he  could  prove  that  it  retained  the  best 
combination  of  observations  with  any  law  of  error.1  An 
analogous  method  of  treating  observations  without  the  sub- 
stitution of  a law  of  error  had  already  been  developed  by 
Laplace  in  his  Theorie  analytique  des  Probabilites  (1812). 
But  it  was  Gauss  who  showed  definitely  that  the  mean  error 
of  a series  of  observations  ought  not  to  be  defined  as  the 
mean  of  the  simple  errors  but  as  the  mean  of  the  squares  of 
the  errors.  And  thus  the  problem  of  finding  a measure  for 
the  reliability  of  a series  of  observations,  which  was  first 
attacked  by  Lambert,  was  solved  finally  by  Laplace  and 
Gauss,  not  only  in  a special  sense  by  the  help  of  Gauss’s 
Law  of  Error,  but  also  in  a general  sense  by  the  use  of  the 
mean  of  the  squared  errors. 

Fechner  took  advantage  of  the  help  afforded  by  the  theory 
of  error  and  he  worked  upon  the  supposition  that  the  pure 
errors,  which  remain  after  being  separated  from  the  constant 
errors,  follow  the  ordinary  laws  of  error.  In  that  case  the 
pure  mean  error  could  be  set  in  reciprocal  relation  to  the 
absolute  value  of  the  difference  sensitivity.  In  the  method 
of  right  and  wrong  cases  he  arrived  at  the  relation  between 

the  relative  number  of  right  cases  | ~ j and  the  distri- 
bution curve  of  the  errors  by  the  consideration  that  a right 
judgment  would  always  occur  if  the  error  process  would 
allow  the  difference  ( 'D ) between  the  two  stimuli  to  appear 
in  its  true  sense.  Judgments  of  equality  Fechner  divided 
equally  between  the  right  and  wrong  cases,  so  that  he  had 
only  to  deal  with  two  categories  of  judgment.  If,  then,  the 
error  process  follows  the  laws  of  Gauss,  then 


hD 

h je-hlDl  dD. 
V TT  0 


1 Theoria  combinationis  observationum  errorthus  minimis  obnoxice, 
1821. 


PSYCHOLOGICAL  METHODS 


227 


It  follows  further  that  out  of  -L  we  can  calculate  h,  and  this 

lb 

is  a measure  for  the  difference  sensitivity.  Since  Fechner 
valued  the  usefulness  of  his  methods  in  the  main  with  respect 
to  testing  Weber’s  Law,  the  knowledge  of  this  value  h was 
sufficient.  If  it  remained  constant  as  long  as  the  stimulus 
difference  D kept  the  same  relation  to  the  normal  stimulus, 
then  the  constancy  of  the  relative  difference  sensitivity  was 
guaranteed  and  with  that  the  validity  of  Weber’s  Law.  Be- 
sides this  there  resulted  a purely  mathematical  relationship 
between  the  method  of  right  and  wrong  cases  and  the  mean 
error  from  the  hypothesis  that  the  measure  of  precision 
(, h ) is  identical  with  the  measure  of  precision  resulting  from 
1 

the  mean  error  . 7"=~ . 

AmV-rr 

The  most  important  changes  in  these  methods  resulted 
from  the  different  ways  in  which  the  judgments  of  equality 
could  be  regarded.  G.  E.  Muller,  in  his  Grundlegung  der 
Psychophysik  (1879),  introduced  a new  point  of  view  in  re- 
gard to  method,  inasmuch  as  he  made  a distinction  between 
the  fact  of  there  being  a difference-threshold  and  the  occur- 
rence of  chance  errors  of  observation.  The  judgments  of 
equality  (z)  are  not  equivalent  to  plus  or  minus  judgments 
of  difference.  They  seem  rather  to  point  to  the  fact  of  the 
threshold  ( i ) being  present,  whereas  the  other  judgments 
come  within  the  scope  of  the  error  process.  In  this  way  he 
arrived  at  the  following  equations: 

¥D-* ) 

L = 1 , h_  Ce-wdD; 

n 2 Vi T0 

fcD  + i)  h(D-i) 

-h^dD-  Je-h^dD) . 

o 


228 


HISTORY  OF  PSYCHOLOGY 


The  relation  between  the  values  h and  i would  thus  become 
an  empirical  question  to  which  an  answer  could  be  given 
by  means  of  experiments. 

The  most  recent  developments  of  the  methods  of  measure- 
ment have  been  in  part  influenced  by  the  attempt  to  find  an 
analytic  presentation  of  the  frequency  of  judgments  which 
shall  be  free  from  the  special  presuppositions  of  Gauss’s 
Law  of  Error.  Indeed,  Fechner  had  tried  to  give  due  atten- 
tion to  the  asymmetry  of  a series  of  observations.  In  an 
asymmetrical  distribution  the  arithmetical  mean  no  longer 
coincides  with  the  most  probable  value.  The  deviations 
must,  therefore,  be  calculated  from  the  “density  value”  or 
median.  We  have,  then,  an  error  curve  on  both  sides  of  the 
median,  and  its  course  is  the  same  as  the  error  curve  that 
is  common  to  both  sides  in  a symmetrical  distribution. 
With  such  a two-sided  or  divided  Gauss’s  Law  Fechner  tried 
to  represent  asymmetrical  types  of  distribution  in  his 
posthumous  KolleJdivmasslehre  (1897). 1 

On  the  other  hand,  along  with  the  distrust  of  the  use- 
fulness of  such  mathematical  aids,  the  inclination  grew  up 
to  determine  psychical  values  without  making  use  of  com- 
plicated formulae  by  means  of  a so-called  immediate  method. 
In  the  “method  of  many  cases”  there  are  not  only  the  above- 
mentioned  categories  of  judgment  but  also  the  cases  of 
decided  difference,  of  more-than- just-noticeable  difference. 
It  had  been  found  necessary  to  give  a different  treatment 
to  these  different  classes  of  judgments,  and  this  led  to  the 
attempt  to  substitute  for  the  analytic  representation  of  the 
frequencies  of  judgment  a frequency  curve  formed  from 
the  empirical  distribution  of  the  judgments  and  then  to 
make  the  area  enclosed  by  such  a curve,  called  by  G.  E. 
Muller  the  ideal  area,  the  basis  for  further  calculation. 
This  emancipation  from  one-sided  mathematical  presuppo- 
1 Cf.  G.  F.  Lipps,  op.  cit.,  pp.  89  ff. 


PSYCHOLOGICAL  METHODS 


229 


sitions  naturally  led  to  an  expansion  of  the  field  in  which 
the  methods  of  psychical  measurement  were  used.  And 
this  was  not  only  true  for  experiments  according  to  the  im- 
pression method,  for  which  the  methods  of  measurement 
were  at  first  particularly  adapted,  but  also  for  many  exper- 
iments according  to  the  expression  method. 

(c)  Connection  with  the  Expression  Methods 

These,  the  most  recent  methods  of  experimental  psy- 
chology, were  originally  physiological  or  registration  methods, 
the  use  of  which  for  psychological  purposes  had  arisen  out 
of  chance  observations.  We  have  already  remarked  briefly 
on  the  reaction  method;1  but  the  other  expression  methods 
also  arose  out  of  physiological  investigations.  After  the 
observations  of  C.  Bell2  on  the  bodily  expressions  of  the 
separate  affections,  the  work  of  Darwin3  is  the  best  known. 
He  found  such  an  intimate  connection  between  the  emo- 
tions and  their  forms  of  expression  that  the  latter  could 
scarcely  exist  if  the  body  remained  passive.  But  the  real 
psychological  importance  of  the  organic  changes  for  the  rise 
of  the  emotions  was  first  pointed  out  by  William  James. 
The  same  idea  was  worked  out  in  greater  detail  by  C.  Lange,4 
who  brought  seven  of  the  most  important  affections,  e.  </., 
disappointment,  anxiety,  fright,  etc.,  into  relation  with  def- 
inite changes  in  voluntary  innervation,  which  are  seen  in 
dilation  or  expansion  of  the  blood-vessels. 

The  chief  advance  in  method  and  technique  is  closely 
allied  to  the  work  of  Mosso  and  Fere.  Mosso  gave  psy- 
chology the  plethysmograph,  which  he  originally  used  for 
the  purpose  of  measuring  changes  in  the  flow  of  blood  to 

1 Cf.  p.  132. 

2 The  Anatomy  and  Physiology  of  Expression,  1806. 

3 The  Expression  of  the  Emotions. 

4 Uber  Gemutsbewegungen.  German  translation  by  Kurella,  1887. 


230 


HISTORY  OF  PSYCHOLOGY 


the  brain.  This  was  done  in  an  indirect  manner,  namely, 
by  measuring  the  corresponding  fluctuations  in  the  volume 
of  blood  in  one  of  the  larger  limbs.1  This  secondary  pur- 
pose of  the  plethysmograph  then  became  changed  into  its 
chief  purpose,  and  the  plethysmographic  curve  became  one 
of  the  most  important  aids  for  registering  the  symptoms  of 
the  feelings  and  the  affections.  Fere2  investigated  chiefly 
muscle  capacity  and  the  distribution  of  blood  in  the  organ- 
ism during  simple  sensory  impressions.  He  found  that  each 
pleasant  sensation  was  accompanied  by  an  increase  and 
each  unpleasant  one  by  a decrease  of  energy  in  the  muscle, 
and  similarly  that  each  feeling  of  pleasure  was  accompanied 
by  an  increase  and  each  feeling  of  displeasure  by  a decrease 
in  the  volume  of  blood  in  the  limbs.  The  experimental 
results  of  Fere  only  partly  coincided  with  the  observations 
drawn  by  Lange  from  practical  life.  This,  along  with  the 
very  small  number  of  results  in  this  field  up  to  that  time, 
led  Lehmann3  to  make  a more  thorough  investigation  of  the 
feelings,  which  at  once  changed  the  whole  point  of  view  for 
the  expression  method.  The  theoretical  discussion  of  the 
results  obtained  by  Lehmann  led  to  numerous  investiga- 
tions of  the  symptomatology  of  the  feelings  and  the  emo- 
tions, and  with  these  results  every  new  theory  of  feeling 
had  to  reckon.4 

The  narrower  group  of  expression  methods  known  as 
the  reaction  methods  are  more  susceptible  to  treatment  by 
the  use  of  the  mathematical  methods  of  psychical  measure- 
ment. Here  there  took  place,  on  a smaller  scale,  the  same 
process  of  development  as  all  methods  of  measurement  go 
through  in  their  metamorphosis  from  physical  to  psychical 

1 Mosso,  Uber  den  Kreislauf  des  Blutes  im  menschlichen  Gehim,  1881. 

2 Sensation  et  Mouvement,  p.  64. 

3 Die  Hauptgesetze  des  menschlichen  Gefiihlslebens.  German  trans- 
lation by  Bendixen,  1892. 

4 Cf.  Chapter  XII,  1. 


PSYCHOLOGICAL  METHODS 


231 


methods.  At  first  interest  centred  only  in  absolute  reac- 
tion times  under  varying  circumstances.  To-day  the  dis- 
tribution of  the  separate  reactions  and  their  relative  values 
have  become  of  no  less  importance  for  the  interpretation 
of  psychical  behavior. 


CHAPTER  IX 


PSYCHICAL  MEASUREMENT 

The  principle  of  psychical  measurement  belongs,  in  the 
main,  to  the  most  recent  psychology.  The  real  foundation 
of  psychical  measurement  by  Fechner  is  preceded  by  a 
fairly  long  preliminary  history.  Out  of  the  controversy 
over  Fechner ’s  psychophysics  two  new  theories  of  psychical 
measurement  arose,  the  differences  between  which  can  be 
most  clearly  perceived  in  their  explanation  of  the  facts 
connected  with  Weber’s  Law.  These  are  the  theories  of 
G.  E.  Muller  and  W.  Wundt. 

i.  Early  History  of  Psychical  Measurement 

Although  we  can  speak  of  the  concept  of  psychical  mea- 
surement only  since  the  time  of  Fechner,  yet  the  formulation 
of  such  a principle  was  prepared  for  by  many  things  before 
his  time.  Remarks  as  to  the  possibility  of  psychical  measure- 
ment arose  particularly  in  connection  with  the  question  as  to 
whether  mathematics  could  be  used  in  the  field  of  psychology. 
A theoretical  discussion  of  the  underlying  idea  precedes  the 
strict  conceptual  formulation  of  it  by  Fechner,  and  this 
mostly  centred  round  the  question  as  to  whether  ideas  of 
measurement  were  applicable  in  connection  with  psychical 
phenomena.  Besides  a few  really  empirical  attempts  at 
measurement,  this  early  history  of  psychical  measurement 
shows  also  the  grouping  together  of  these  observations  into 
a law,  i.  e.,  Weber’s  Law,  which  from  that  time  on  became 
the  principal  fact  in  the  field  of  psychical  measurement. 

232 


PSYCHICAL  MEASUREMENT 


233 


(a)  The  Earliest  Suggestions  of  Psychical  Measurement 

The  opinion  that  psychical  phenomena  cannot  be  mathe- 
matically represented  is  of  very  early  origin.1  We  find  it 
already  in  Malebranche2  in  his  statement  that  we  can  have 
clear  ideas  of  number  and  extent,  but  that  in  comparing 
mental  states  we  can  perceive  clearly  only  differences  in 
quality  which  can  never  be  represented  by  a quantitative 
expression.  Malebranche  drew  a sharp  line  of  distinction 
between  the  physical  stimulus  and  the  corresponding  mental 
state.  The  relations  between  our  tone  sensations  certainly 
point  to  regular  relations  with  the  objective  number  of 
oscillations,  but  the  differentiation  of  different  tones  takes 
place  not  by  means  of  clear  ideas  but  by  means  of  the  feelings. 

Leibniz  further  prepared  the  way  for  the  use  of  the  mathe- 
matical point  of  view,  inasmuch  as  he  carried  over  to  sensa- 
tion qualities  the  principle  of  continuity,  which  he  had  for- 
mulated with  such  clearness  for  mechanical  phenomena.3 
The  sensation  quality  of  yellow  or  of  white  comes  under  the 
concept  of  a continuous,  extended  quantity.  Of  course, 
Leibniz  thought  that  he  was  here  dealing  only  with  an  anal- 
ogy of  his  concept  of  quantity,  which  in  metaphysics  and, 
therefore,  in  psychology  could  not  be  directly  used. 

In  the  eighteenth  century  our  problem  centres  around  the 
question  as  to  whether  psychical  phenomena,  in  their  char- 
acter of  intensive  quantities,  could  be  classed  under  concepts 
of  measurement  which  presuppose  a summation  of  elements. 
After  Wolff  had  set  up  the  demand  for  a science  of  psycho  m- 
etry,  Ploucquet4  questioned  very  decidedly  the  possibility  of 

1 Cf.  Itelson,  Arch.  f.  Gesch.  der  Phil.,  Bd.  Ill,  1890,  pp.  282  ff. 

2 Recherche  de  la  verite,  1675,  XI. 

3 Math.  Schr.,  edited  by  Gerhardt,  Bd.  VI,  pp.  99  /. 

4 Commentatio  de  Arte  Charaderistica,  Einleitung  zu  Methodus  cal- 
culandi  in  logicis,  1763. 


234 


HISTORY  OF  PSYCHOLOGY 


using  the  number  concept  in  regard  to  intensive  quantities. 
He  opposed  the  universal  characteristic  set  up  by  Leibniz 
as  well  as  the  psychometry  of  Wolff . The  intensity  of  any 
sensation  can  in  no  way  be  made  up  of  parts.  If  I add  to  a 
certain  light  a less  intensive  one,  the  first  light  does  not 
thereby  become  brighter,  as  it  ought  to  if  the  two  lights 
were  simply  added.  Kant  for  some  time  entertained  the 
thought  of  such  a composition  of  sensations  out  of  a number 
of  equal  parts.  He  promised  in  a letter  to  Schiitz  (1785) 
to  add  an  appendix  on  the  theory  of  the  soul  to  his  Meta- 
physical Foundations  of  Natural  Science.  The  basic  principle 
of  the  anticipations  of  sense-impressions  ought  to  help  us  to 
a “Mathesis  intensorum.”  It  is  well  known  that  the  mathe- 
matical principles  of  pure  reason  teach  us  “ how  phenomena, 
according  to  their  appearance  or  according  to  the  reality 
of  their  perception,  can  be  produced  according  to  the  rules 
of  a mathematical  synthesis,  and  that,  therefore,  in  the  one 
case  as  in  the  other,  number  values  can  be  used.  I can,  for 
example,  put  together  and  decide  a priori  that  the  intensity 
of  the  sensations  of  sunlight  is  equal  to,  say,  two  hundred 
thousand  times  the  brightness  of  the  moon.”  Kant,  mean- 
while, did  not  draw  any  conclusion  of  interest  to  psychology 
from  this,  for  precisely  the  supposed  impossibility  of  using 
mathematical  concepts  of  size  became  his  chief  argument 
against  the  possibility  of  psychology  being  regarded  as  a 
science.1  It  is  possible  that  the  influence  of  Ploucquet  led 
to  this  change  in  his  opinions. 

Just  about  this  time  Eberhard2  came  surprisingly  near  to 
Fechner’s  principal  thought.  He  finds,  in  connection  with 
the  limitation  of  mental  power,  “that  the  comparison  of 
the  values  of  images  according  to  the  degree  of  clearness 

1 Cf.  pp.  151  /. 

2 Allgemeine  Theorie  des  Denkens  und  Empfindens,  1776  and  1786, 


PSYCHICAL  MEASUREMENT 


235 


leads  to  a mathematics  of  the  soul.  In  the  comparison  of 
sensations  with  each  other  the  unit  of  measurement  would 
have  to  be  an  unnoticed  image  which,  of  course,  would  be 
useless  for  this  purpose  just  because  it  is  unnoticed.” 

In  the  nineteenth  century  the  old  arguments  for  and 
against  psychical  measurement  are  repeated.  Galuppi1  op- 
posed the  possibility  of  adding  sensation  intensities  with  the 
argument  that  quantitative  determination  always  belongs 
to  the  object  of  sensation  but  never  to  the  sensation  itself. 
Others  regarded  the  possibility  of  psychical  measurements 
as  quite  natural  and  agreed  to  it  as  a matter  of  course. 
In  the  long-forgotten  Psychologie  of  Eschenmayer  we  note 
the  remark  that  “ a perfect  theory  of  the  senses  must  bring 
everything  qualitative  that  works  upon  our  senses  into 
measurable  relations  subject  to  the  calculus,  and  each  quality 
must  possess  a certain  value  in  dynamics.”  2 

(b)  Weber’s  Law  and  Its  Preliminary  History 

The  anticipations  of  Weber’s  Law  do  not  take  us  back  into 
the  field  of  the  old  psychology.  Here,  if  anywhere,  we  see 
the  origin  of  one  of  the  most  important  laws  of  psychology 
based  upon  the  experiences  gathered  during  observations 
made  for  the  purposes  of  natural  science. 

Errors  of  observation  and  the  inaccuracy  of  our  sense- 
perceptions  led  to  an  investigation  of  the  subjective  factors 
of  sense-perception.  Older  than  the  attempts  to  arrive  at  a 
quantitative  determination  of  the  capacity  of  human  sense- 
organs  is  the  knowledge  that  there  certainly  exists  a limit 
to  their  capacity.  Even  if  we  neglect  for  the  moment  the 
very  general  recognition  of  the  relativity  of  sensation,  we 
can  trace  a special  form  of  this  thought,  which  to-day  gets 

1 Saggio  filosoftco  sulla  critica  della  conoscenza,  1819. 

2 Op.  dt.,  1822,  p.  48. 


236 


HISTORY  OF  PSYCHOLOGY 


the  name  of  the  determination  of  the  difference-threshold, 
right  back  to  the  Scholastic  Buridan.  He  pointed  out  vari- 
ous changes  of  our  perceptions  due  to  purely  subjective  con- 
ditions, as,  for  example,  the  fact  that  gray  near  black  seems 
whiter  than  gray  near  white.  In  this  connection  he  notes 
that  not  every  minute  addition  to  the  outer  stimulus  cor- 
responds to  a change  in  the  sensation,  and  this  is  really  a rec- 
ognition of  the  fact  of  the  difference-threshold.1 

The  first  quantitative  experiments  in  modern  times  were 
performed  in  the  field  of  visual  sensations.  Lambert  set 
himself  the  task,  in  his  Photometry ,2  to  determine  the  capacity 
of  the  eye  for  the  differentiation  of  brightness.  Since  light 
cannot  be  measured  by  a photometer,  like  warmth  by  a ther- 
mometer, we  have  to  depend  solely  upon  our  eye  for  the 
determination  of  the  intensity  of  light,  and  the  judgments 
of  the  eye  are  unreliable  for  various  reasons.  The  contrac- 
tions and  dilations  of  the  pupil,  the  changes  in  sensitivity  of 
the  optic  nerve  according  to  the  surrounding  illumination, 
are  all  causes  that  may  give  rise  to  illusions.  And,  besides 
these  things,  it  is  a common  characteristic  of  all  sensations 
for  the  stronger  to  suppress  the  weaker.  A candle  in  the 
sunlight  seems  to  possess  no  brightness,  and  yet  the  light  of 
this  same  candle  may  so  suppress  the  light  that  rises  from 
decaying  wood  as  to  make  the  latter  appear  as  if  it  did 
not  exist.3 

His  further  investigations  are  based  upon  his  “axiom  of 
photometry,”  according  to  which  a phenomenon  is  the  same 
as  long  as  it  affects  the  same  eye  in  the  same  way.  If  the 
eye  looks  at  two  juxtapositive  objects  at  the  same  time,  it 
is  able  to  give  a judgment  as  regards  likeness  or  difference; 

1 De  anima,  II,  14,  /.  12  c : sic  etiam  de  luce  tu  non  percipies  statim 
parvum  augmentum  lucis. 

2 Photometria  sive  de  mensura  et  gradibus  luminis,  colorum  et  umbrae , 
1760. 

s Op.  cit.,  p.  10. 


PSYCHICAL  MEASUREMENT 


237 


but  a definite  statement  of  the  degree  by  which  two  bright- 
nesses differ  is  not  possible.  This  remark  is  of  special  im- 
portance for  us  because  of  the  later  controversy,  which  arose 
out  of  the  conception  of  the  more  than  just-noticeable  dif- 
ference. If,  however,  the  eye  judges  two  brightnesses  as 
equal,  we  are  forced  to  assume  that  the  brightnesses  closely 
approximate  equality.  And  yet  there  is  always  a minimal 
difference  present  which  escapes  observation.  In  order  to 
determine  this  difference,  Lambert  illuminated  a perfectly 
white  and  smooth  wall  by  means  of  a candle.  Shielding 
the  eye  from  the  direct  light  and  standing  some  distance 
away,  he  measured  off  the  region  within  which,  according 
to  the  judgment  of  the  eye,  the  brightness  of  the  wall  ap- 
peared to  be  constant.  The  size  of  this  region  of  no  longer 
noticeable  difference  decreased  with  the  absolute  brightness; 
even  the  relation  to  the  first  brightness  was  not  a constant 
quantity,  for  it  increased  from  .04  to  .07  with  the  decrease 
in  brightness.  This  problem,  which  led  Lambert  right  up 
to  the  facts  of  Weber’s  Law,  was  not  pursued  further  by 
him;  he  was  satisfied  in  showing  that  this  unnoticeable  or 
just-noticeable  difference  in  brightness  was  very  small. 

Bouguer,  a contemporary  of  Lambert,  possessing  perhaps 
less  talent  for  scientific  observation  but  more  favored  by 
luck  in  his  experimental  work,  carried  on  similar  experiments 
on  the  differentiation  of  given  brightnesses.1  His  method 
has  become  known  under  the  name  of  Bouguer’s  shadow 
experiment.  One  source  of  light  (Xx)  is  gradually  moved 
backward  from  a rod  (s)  until  the  shadow  of  this  becomes 
unnoticeable  on  a field  illuminated  by  a second  source  of 
light  ( L2 ),  of  the  same  intensity  as  Lv  from  a constant  dis- 
tance. In  this  way  Bouguer  found  that  a given  light  in- 
tensity must  be  increased  by  -fa  if  the  increase  is  to  be 

1 Traiii  d’optique  sur  la  gradation  de  la  lumiere  par  Lacaille,  1760, 
p.  51. 


238 


HISTORY  OF  PSYCHOLOGY 


noticeable.  And  this  proportion  proved  itself  to  be  inde- 
pendent of  the  light  intensity.  Just  as  a loud  noise  prevents 
us  from  hearing  a weaker  one,  so  in  the  presence  of  a bright 
light  we  are  not  able  to  see  another  of  much  less  intensity 
if  both  of  them  affect  the  same  part  of  the  retina.  Arago1 
later  repeated  these  experiments  of  Bouguer  and  extended 
them  by  making  use  of  colored  lights.  He  declared  pos- 
itively that  the  just-noticeable  relative  difference  remained 
constant  for  different  brightnesses.2 

In  an  extensive  investigation  on  electrical  photometry, 
Masson3  described  a new  and  simple  method  for  the  deter- 
mination of  the  just-noticeable  difference.  He  set  in  rota- 
tion white  disks,  upon  which  a short  piece  of  a narrow  black 
sector  of  variable  breadth  was  introduced.  By  means  of 
fusion  there  appeared  on  the  disk  a gray  band,  which  by 
varying  the  breadth  of  this  black  sector  could  be  reduced 
until  just  noticeable.  These  disks  of  Masson  have  found 
their  place  in  psychophysics  and  have  proved  themselves 
very  useful.  The  independence  of  the  size  of  the  sector 
(thus  reduced  to  a gray  band  just-noticeably  different  from 
the  background)  from  the  intensity  of  the  absolute  bright- 
ness shows  immediately  that  the  just-noticeable  relative 
brightness  differences  are  constant,  and  this  is  precisely 
the  problem  of  Weber’s  Law. 

The  usual  immediate  judgments  of  the  brightness  dif- 
ferences of  stars  in  astronomy  were  a further  cause  prompt- 
ing to  photometrical  investigations.  Since  the  time  of  Hip- 
parchus the  stellar  magnitudes  had  been  divided  into  classes 
according  to  the  impression  of  their  brightness.  Each 
class  was  separated  from  the  next  by  a supposed  equal 
degree  of  brightness.  Since  the  investigations  of  J.  Her- 

1 Ann.  de  Chim.  et  de  Phys.,  1845,  t.  XIV,  p.  150. 

2 Populare  Astronomie,  edited  by  Hankel,  I,  p.  168. 

3 Ann.  de  Chim.  et  de  Phys.,  1845,  t.  XIV,  p.  150. 


PSYCHICAL  MEASUREMENT 


239 


schel,  which  have  now  been  authoritative  for  a long  time, 
the  true  brightnesses  of  these  stellar  classes  form  a de- 
creasing quadratic  series  of  the  form  1,  T\.  . . . 

Fechner  later  expected  to  find,  by  the  right  choice  of  the 
mean  brightness  of  a star  of  the  first  magnitude,  that  the 
data  observed  could  be  represented  with  greater  truth  by 
a diminishing  geometrical  progression.1  The  meaning  of 
a constant  brightness  proportion  for  the  different  classes 
of  stars  could,  however,  only  arise  out  of  the  fundamental 
laws  of  Fechner’s  psychophysics.  More  immediately  lead- 
ing to  the  facts  of  Weber’s  Law  were  the  investigations  of 
the  accuracy  with  which  such  photometrical  determinations 
of  the  objective  brightness  of  stars  could  be  made.  Stein- 
heil2  tested  on  the  prism  photometer  the  dependence  of 
the  size  of  the  error,  which  is  made  in  equating  two  light 
intensities,  upon  the  size  of  the  intensities  to  be  compared. 
His  observations  showed  that  it  is  possible  to  arrange  a 
similar  brightness  on  two  fields  with  great  exactness.  The 
uncertainty  of  each  separate  judgment  of  this  kind  does  not 
exceed  zt  of  the  total  brightness,  however  great  or  little 
this  may  be.3  Here,  then,  we  find  formulated  for  light 
intensity  that  fact  which  Weber  recognized  as  a universally 
valid  one. 

In  accordance  with  the  wide  range  which  Weber’s  Law 
covers,  we  note  that  its  preliminary  history  branches  out  into 
very  different  directions.  All  the  experiments  we  have  so 
far  considered  were  based  upon  the  peculiarities  of  the  sen- 
sations. In  the  theory  of  the  feelings,  however,  we  find 
also  an  independent  starting-point  for  similar  considera- 
tions which  have  a mathematical  tradition,  although  the 
feelings  would  certainly  prove  themselves  one  of  the  most 

1Elem.  d.  Psych.,  pp.  160  ff. 

2 “ Elemente  der  Helligkeitsmessungen  am  Stemenhimmel,”  in  Abh. 
d.  maih.-physik.  Kl.  d.  Konigl.  bay.  Akad.,  1837. 

3 Op.  cit.,  p.  14. 


240 


HISTORY  OF  PSYCHOLOGY 


unsuitable  departments  for  the  empirical  confirmation  of 
any  such  mathematical  laws.  In  the  dependence  of  the  so- 
called  “fortune  morale”  upon  the  “fortune  physique”  we 
have  even  an  anticipation  of  the  formula  in  which  Fech- 
ner  expressed  the  facts  of  Weber’s  Law.  Bernoulli1  for- 
mulated the  principle  that  the  value  of  external  possessions 
is  to  be  measured  by  the  increase  which  accrues  to  the  pos- 
sessor. Any  increase  in  value  is  merely  an  increase  that 
is  proportional  to  the  external  goods  already  possessed. 
He  expressed  this  principle  by  a differential  formula  and 
by  the  logarithmic  relation  that  results.  Later  on,  Laplace2 
argued  from  the  difference  between  the  absolute  and  rel- 
ative value.  If  the  latter  is  reciprocal  to  the  total  pos- 
sessions (a:)  to  which  it  is  added,  then  the  increase  of  the 

k.dx 

“fortune  morale”  can  be  expressed  by  - — — , where  A;  is  a 

constant.3  If  y denotes  the  “fortune  morale”  correspond- 
ing to  the  “fortune  physique”  (a;),  then  it  follows  that 
y = k . log  x + log  h;  the  arbitrary  constant  h can  be  found 
from  the  two  dependent  values  x and  y.  And,  lastly,  Pois- 
son4 arrived  at  the  same  thought.  He  called  the  relative 
increase  in  value  “esperance  morale”  in  contrast  to  “esper- 
ance  mathematique.”  Above  all,  the  practical  application 
of  this  principle  seemed  of  importance  to  him,  although 
to  us  it  appears  very  peculiar  with  its  supposed  proof  of 
the  rules  of  practical  life  by  means  of  the  integral  calculus. 

Weber  himself  formulated  the  law  which  bears  his  name 
in  1834,  basing  it  upon  experiments  that  he  had  car- 
ried on  in  different  departments  of  sensation.  If  we  no- 
tice a difference  in  comparing  two  values,  we  do  not  per- 
ceive the  difference  of  the  values  but  the  relation  of  the 

G Specimen  theories  novee  de  mensura  sortis,  1738. 

2 Theorie  cmalytique  des  Probability,  p.  187. 

3 Op.  cit.,  p.  432. 

4 Recherches  sur  la  probability,  p.  72. 


PSYCHICAL  MEASUREMENT 


241 


difference  to  the  two  values  we  are  comparing.1  In  the 
now  classical  monograph  Der  Tastsinn  und  das  Gemeingefiihl 
(1846),  he  summed  up  the  results  of  his  investigations  on 
the  smallest  just-noticeable  differences  of  lines  and  weights, 
and  laid  it  down  that  the  recognition  of  the  just-noticeable 
difference  is  dependent  entirely  upon  the  relation  of  the 
difference  to  the  total  value. 

As  supposed  evidence  he  also  brought  forward  the  results 
of  Delezenne,  who  thought  he  had  proved  that  a tone  always 
becomes  just-no ticeably  out  of  tune  at  the  same  relative 
difference  in  the  number  of  oscillations.  The  investigations 
of  Delezenne  at  the  end  of  the  eighteenth  century  had  fol- 
lowed the  dispute  between  Marpurg  and  Kirnberger,  the 
supporters  of  the  arhythmic  and  rhythmic  theory  of  tem- 
perature. Among  a great  number  of  fruitless  theoretical 
discussions  the  idea  arose  that  possibly  because  of  the  im- 
perfection of  the  organ  of  hearing  the  ultimate  deviations 
from  the  pure  interval,  which  can  never  be  avoided  on  an 
instrument,  remain  unnoticed.2  It  is  strange  that,  in  spite 
of  this  appeal  to  psychological  experience,  experimental  in- 
vestigation was  not  taken  up  in  Germany.  Delezenne  was 
the  first  to  start  his  famous  experiments  in  order  to  con- 
tradict the  statement  of  Galin  that  one  could  never  get  any 
exact  knowledge  of  the  length  of  the  strings  that  produce 
the  tones  of  the  scale.3  In  contradistinction  to  these  only 
the  most  recent  investigations  have  proved  that  the  abso- 
lute difference-threshold  is  constant. 

In  comparison  with  the  earlier  formulation  of  the  law  of 

1 Ann.  Anot.,  p.  172:  In  observando  discrimine  rerum  inter  secompara- 
tarum  non  differentiam  rerum  sed  rationem  differentiae  ad  magnitudinem 
rerum  inter  se  comparatarum  percipimus. 

2 Cf.  the  article  “ Temperatur,”  by  Sulzer,  Allgemeine  Theorie  der 
schonen  Kiinste,  1778,  Bd.  II,  p.  283. 

3 “ Memoires  sur  les  valeurs  numeriques  des  notes  de  la  Gamme,”  in 
Recueil  des  travaux  de  la  soc.  des  scienc.,  de  I’agric.  et  des  arts  de  Lille, 
1826  et  1827,  pp.  1 ff.  ’ 


242 


HISTORY  OF  PSYCHOLOGY 


1834,  the  later  one  undoubtedly  shows  a certain  restric- 
tion of  the  law.  It  does  not  include  so  many  of  the  facts  of 
experience  as  the  former  did,  and  yet  in  its  generalization 
of  the  observed  facts  it  remains  a splendid  example  of  Web- 
er’s cautious  but,  nevertheless,  always  ingenious  method  of 
investigation.  Above  all,  this  regularity  in  the  phenomena 
did  not  yet  appear  to  him  as  a principle  for  the  measure- 
ment of  sensation.  He  rather  looked  upon  the  immediate 
recognition  of  the  relations  between  whole  values  as  a most 
interesting  psychological  phenomenon.1  He  did  not  in  any 
way  anticipate  the  conclusions  which  later  on  Fechner  drew 
from  this  law.  It  was  for  Weber  only  applicable  to  the 
value  of  the  just-noticeable  difference. 

2.  The  Founding  of  Psychical  Measurement  by  Fechner 

The  decisive  step  leading  from  all  these  separate  cases 
to  the  conception  of  a new  principle  was  taken  by  Fechner. 
In  him  the  older  attempts  to  find  a mathematical  principle 
of  measurement  and  the  newer  experimental  methods  and 
ideas  meet.2  First  of  all,  Fechner  developed  a principle  of 
measurement  for  sensitivity  in  connection  with  facts  of  ex- 
perience. We  are  able,  for  example,  to  make  an  attempt 
at  measuring  the  size  of  those  stimuli  which  produce  equally 
large  sensations  or  equally  large  differences  of  sensation. 
But  in  these  concepts  of  absolute  sensitivity  and  of  differ- 
ence sensitivity  assumed  here  we  have  not  yet  arrived  at  a 
principle  for  the  measurement  of  sensation.  If  the  size  of 
the  sensation  could  be  considered  proportional  to  the  size 
of  the  stimulus,  then  it  would  be  easy  to  pass  on  to  some 
kind  of  measurement  of  the  sensations.  Such  an  assump- 
tion is,  however,  not  proved  by  any  facts.  To  find  such 
we  must  first  of  all  discover  the  function  existing  between 
1 Op.  cit.,  p.  561.  2 Cf.  p.  129. 


PSYCHICAL  MEASUREMENT 


243 


the  two  elements,  stimulus  and  sensation,  and  to  do  this 
we  have  to  depend  upon  the  judgment  of  equality  within 
the  field  of  sensation — the  only  judgment  possible  in  our 
experience.  In  theory,  then,  this  measure  of  sensation 
must  be  obtained  by  dividing  up  the  sensation  into  equal 
increments,  out  of  which  the  sensation  is  built  up,  begin- 
ning with  zero.  The  number  of  these  increments  is  deter- 
mined by  the  number  of  the  corresponding  additions  of 
stimulus,  which  are  able  to  produce  equal  additions  of  sen- 
sation. To  arrive  at  this  function  we  make  use  of  Weber’s 
universally  valid  law  that  equal  relative  additions  of  stimuli 
correspond  to  equal  additions  of  sensation. 

The  following  is  the  most  important  of  the  mass  of  for- 
mulse  which  Fechner  worked  out:  If  /3  is  the  stimulus  to 
which  a very  small  addition,  d/3,  is  made,  then  the  relative 

increase  of  the  stimulus  is  Let  the  sensation  de- 


pendent upon  the  stimulus  /3  be  called  7,  and  a very  small 
change  in  the  sensation  be  dy.  Weber’s  Law  can  then  be 

expressed  by  the  equation  dy  = — , where  K is  a con- 


stant. This  equation  was  called  by  Fechner  the  funda- 
mental formula.  If  we  integrate  we  get  y —K  log  /3-f  C, 
where  C is  the  constant  of  integration.  If  C is  determined 
by  the  condition  that  the  sensation  7 disappear  at  the  thresh- 
old value  of  the  stimulus  /3=b,  then  we  have  0 = K log 
6+  C and,  therefore,  C — -K  log  b and  7 —K  ( log  /3  — log  b). 
This  equation  is  the  measurement  formula.  Its  formula- 
tion would  be  illusory  if  the  fact  of  the  threshold  did  not 
exist.  For  example,  if  the  sensation  disappeared  only  when 
the  value  of  the  stimulus  was  nothing,  then  we  would  get 
for  C an  infinite  value  and  no  finite  expression  could  be 
given  for  any  sensation  value. 

We  need  yet  another  formula  as  a measure  for  the  sensed 


244 


HISTORY  OF  PSYCHOLOGY 


differences.  Let  u be  the  difference  that  is  sensed  between 
the  sensations  y and  y',  and  4>  the  corresponding  stimulus 
/3 

relation  and,  further,  let  the  relative  threshold  v have 

the  same  relation  to  <p  as  the  simple  threshold  b to  the 
stimulus  /3,  then  it  follows  that  u = k ( log  $ —log  v).  This 
equation,  the  so-called  formula  for  difference  measurement, 
could  be  looked  upon  as  the  one  approximating  most  closely 
to  Weber’s  ideas.  And  yet  what  is  for  Fechner  most  im- 
portant in  Weber’s  experiments  is  not  the  fact  that  a just- 
noticeable  difference  in  sensation  follows  a relatively  pro- 
portionate stimulus,  but  rather  the  supposedly  equivalent 
fact,  namely,  that  in  such  a case  an  equal  difference  in 
sensation  is  observed.  Only  the  analogy  between  the  dif- 
ference-threshold and  the  stimulus-threshold  allows  this  for- 
mula for  the  measurement  of  difference  to  be  deduced  from 
the  first  or  measurement  formula. 

For  Fechner  an  important  supplement  to  Weber’s  Law 
was  his  so-called  parallel  law,  which  stated  that  if  the  sen- 
sitivity for  two  stimuli  changed  in  equal  proportion  the 
sensation  of  their  difference  remained  the  same.  This  law 
forms  one  of  the  bridges  between  outer  and  inner  psycho- 
physics, since  it  carries  over  Weber’s  Law  to  the  psycho- 
physical activity  produced  by  the  stimulus.  This  inner 
psychophysics  of  Fechner  has  remained  a realm  of  shadows. 
But  the  underlying  thought  of  his  outer  psychophysics,  his 
bold  coupling  of  the  psychical  to  the  physical  world  by 
means  of  an  elegant  mathematical  formula,  even  if  it  was  to 
be  contradicted  later,  started  a movement  of  psychological 
thought  the  after  effects  of  which  are  still  with  us  at  the 
present  day. 


PSYCHICAL  MEASUREMENT 


245 


3.  Discussions  Arising  out  of  Fechner’s  Psychophysics 

(a)  Objections  and  Attacks 

The  two  decades  following  the  publication  of  Fechner’s 
Psychophysik  (1860)  are  filled  with  polemics  directed  against 
his  proud  system  of  thought.1  We  find  at  first  attempts 
made  so  to  transform  Fechner’s  formulae  that  they  may  more 
accurately  represent  the  facts  of  observation.  A need  of 
this  kind  was  felt  by  Helmholtz2  in  the  field  of  visual  sen- 
sations in  regard  to  the  upper  and  lower  deviations  from 
Weber’s  Law,  which  are  much  greater  than  Fechner  had  sup- 
posed from  his  own  experiments.  To  do  justice  to  them, 
Helmholtz  formulated  the  following  differential  equation : 


8 = c-S/3 

^ (a+/3)  (H  + /3) 

In  this  equation  c,  a,  and  A are  constants;  a is  the  weak 
inner  excitation  independent  of  the  outer  stimulus;  A is  a 
very  high  value.  If  a disappears  in  regard  to  ft,  and  in 
regard  to  A,  the  equation  is  transformed  into  Fechner’s 
fundamental  formula.  Integration  leads  to: 


7 = 


c 

A— a 


. log  nat 


a4~  ft 

A + i 3 


Const. 


This  formula  of  measurement  is  based  upon  Fechner’s  con- 
siderations of  the  scope  of  the  stimulus;  but  besides  this 
it  indicates  the  maximum  of  the  relative  difference  sensi- 
tivity. If  Helmholtz  ever  did  agree  with  the  psycho- 
physical interpretation  that  Fechner  gave  to  Weber’s  Law, 

1 For  a summary  of  these  controversies,  see  Fechner,  Revision  der 
Hauptpunkte  der  Psychophysik,  1877,  and  In  Sachen  der  Psychophysik, 
1882. 

2 Physiol.  Optik,  1867,  p.  313. 


246 


HISTORY  OF  PSYCHOLOGY 


it  was  obviously,  as  in  this  case,  the  alleged  simplicity  of  the 
explanation  which  had  attracted  him.1 

Aubert2  raised  much  severer  objections  against  the  va- 
lidity of  Weber’s  Law.  Without  going  beyond  the  range 
of  thought  involved  in  Fechner’s  psychophysics,  he  stated 
the  results  of  his  experiments  on  the  supposition  that  the 


S/3 


values  stand  in  inverse  relation  to  the  logarithms  of 


(3,  if  the  logarithm  of  /3  for  a certain  definite  small  value  of 

8/3  . 

p and  also  the  corresponding  is  put  equal  to  1. 


Numerous  objections,  which  were  directed  against  the 
assumed  experimental  verification  of  Weber’s  Law,  were 
brought  forward  by  Mach.3  But  more  important  was  his 
contention  that  the  formulae  of  outer  psychophysics  could 
not  by  any  means  be  carried  over  to  inner  psychophysics. 
The  sensation  depends  directly  upon  the  stimulus  but,  on 
the  other  hand,  indirectly  upon  the  psychophysical  activ- 
ity. This  psychophysical  activity  or  nervous  excitation  and 
the  sensation  run  continually  parallel  with  each  other  and 
cannot  be  anything  else  than  proportional  to  each  other. 

This  proportional  relationship  between  sensation  and 
psychophysical  activity  introduced  into  the  discussion  by 
Mach  was  made  by  Bernstein4  the  foundation  for  a purely 
physiological  interpretation  of  Weber’s  Law.  Bernstein  rec- 
ognized Fechner’s  formulae  of  measurement  but  put  the 
sensation  proportional  to  the  number  of  ganglion  cells  in 
the  brain,  through  which  the  nervous  excitation  passes.  Let 
the  whole  space  which  it  fills  be  called  S and  its  density 


4C/.  pp.  126/. 

2 Physiologie  der  Netzhaut,  1865,  pp.  49  ff. 

3 “liber  die  physiologische  Wirkung  raumlich  verteilter  Lichtreize,”  in 
Wiener  Sitzungsber.,  1868,  Bd.  68,  p.  11. 

4 “ZurTheoriedesFechnerschenGesetzesder  Empfindung,”  in  Reichert - 
Duboissches  Archiv,  1868,  pp.  388  ff.  Untersuchungen  iiber  den  Erre- 
gungsvorgang  im  Nerven-  und  Muskelsysteme,  1871,  pp.  166  ff. 


PSYCHICAL  MEASUREMENT 


247 


a.  Then  according  to  our  fundamental  hypothesis  the  sen- 
sation 7 will  be  measured  by  7 = a.S.  Further,  S must  be 
expressed  as  a function  of  the  stimulus  /3  and  of  the  thresh- 
old value  b,  with  which  the  nervous  excitation  y disappears 
on  the  border  of  the  circle  through  which  it  radiates.  The 
loss  that  y suffers  after  it  has  passed  through  the  spatial 
element  must,  because  of  the  weakening  of  y due  to 
its  spreading  out,  be  put  proportional  to  the  growth  of 
a?  to  aS?,  to  the  intensity  of  y at  the  border  of  the  space 
measured  by  s,  and,  thirdly,  to  a constant  k,  which  takes  into 
consideration  the  specific  resistance  of  the  central  elements. 
Therefore,  we  have  8y  = —k.a  .y  .S? 
and 


log  nat  y = — has  + Const. 
If  y = /3,  then  s = 0;  and  if  y = b,  then  s — S. 
Therefore 

/3 

k . a . S = log  nat 


Using  our  first  equation,  we  now  get 


7 


1 

k' 


log  nat 


P 

b’ 


which  expresses  the  empirical  facts  of  Weber’s  Law.  The 
most  doubtful  of  Bernstein’s  presuppositions  is  that  the 
nervous  excitation  becomes  weakened  through  each  cell  in 
proportion  to  its  intensity  as  it  reaches  each  cell,  because 
the  nervous  impulse  is  nowhere  limited  by  any  such  law. 
Of  course  the  fact  of  the  stimulus-threshold  is  advanced  and 
made  to  mean  a degree  of  nervous  excitation  that  is  too 
small  to  be  carried  along  to  the  brain;  but  this  external 
analogy  does  not  help  much.  In  spite  of  this,  Bernstein’s 
hypothesis  was  the  model  for  a whole  series  of  attempts 
at  a physiological  interpretation. 

Of  more  importance  than  such  hypothetical  physiological 
constructions  were  the  discussions  as  to  the  purely  psycho- 
logical consequences  of  Fechner’s  law.  One  line  of  thought, 


248 


HISTORY  OF  PSYCHOLOGY 


which  was  very  often  to  be  repeated  later,  was  based  upon 
the  method  of  middle  gradations  used  by  Plateau.1  Pla- 
teau maintained  that  the  sameness  of  the  impressions  of  a 
copperplate  engraving  in  very  different  illuminations  could 
be  best  explained  by  the  fact  that  the  relations  of  the  sen- 
sations and  not  their  differences  remained  constant.  Pla- 
teau put  the  formula  of  measurement  in  this  form: 

7 = k.fip, 

where  p and  k are  constants  and  p always  smaller  than  1. 
The  fundamental  formula  must  therefore  take  this  form: 

87  B/3 

In  general,  Brentano  shows  his  agreement  with  such  a for- 
mula when  he  explains  the  fact  of  Weber’s  Law  by  saying 
that  every  increase  of  sensation  is  noticeable  as  equal  if 
it  retains  the  same  relation  to  the  intensity  of  the  sensa- 
tion to  which  it  is  added.2  Apart  from  this,  Brentano  ques- 
tioned altogether  the  possibility  of  using  any  principles  of 
measurement  in  regard  to  psychical  phenomena.  This  po- 
sition is  a necessary  consequence  of  the  point  of  view  of 
which  he  made  use  in  distinguishing  between  psychical  and 
physical  phenomena.3  This  hypothesis  of  a constant  rela- 
tion between  two  just-noticeably  different  sensations  gained 
a fairly  wide  recognition.  Uberhorst 4 expressed  it  by  say- 
ing that  similar  sensations,  which  can  just  be  differentiated, 
always  differ  from  each  other  by  a small  fraction  of  their 
own  intensity.  This  was  the  form  that  many  psychologists 
considered  the  simplest  expression  of  Weber’s  Law. 

Delbceuf’s6  position  has  been  somewhat  changeable.  He 
originally  assumed  that  each  sense-organ,  even  without  being 

1 Cf.  p.  222.  2 Psychol,  v.  errip.  Standp.,  1874,  p.  90. 

3Cf.  pp.  84,  160/. 

4 Die  Entstehung  der  Gesichtswahrnehmung,  1876. 

6 Etude  psychophysique,  Bruxelles,  1873. 


PSYCHICAL  MEASUREMENT 


249 


affected  by  a stimulus,  was  in  a state  of  excitation  (c).  To 
avoid  the  threshold  and  negative  sensation  values  he  put 


from  which  we  get 


h = K- 


S/3 

c + £’ 


7 = K log 


c 


This  hypothesis  seemed  to  be  verified  by  experiments  which 
he  carried  on  in  reference  to  brightness  according  to  the 
method  suggested  by  Plateau,  and  Fechner  welcomed  this 
as  a specially  convincing  verification  of  his  law. 

Delboeuf1  himself,  however,  later  arrived  at  other  con- 
clusions. He  formed  the  idea  that  the  oscillatory  activity 
of  the  sensory  nerves,  the  value  of  which  he  denoted  by 
p,  tries  to  get  into  equilibrium  with  the  activity  (p')  of  the 
outer  stimulus.  A sensation  exists  as  long  as  the  equilib- 
rium is  not  attained,  and  according  as  p or  p'  has  the  upper 
hand  there  results  a negative  (<?.  g.,  cold,  dark)  or  a posi- 
tive ( e . g.,  warmth,  light)  sensation.  As  long  as  the  nerve 
has  not  yet  reached  a state  of  equilibrium  along  with  the 
stimulus  it  remains  in  a state  of  strain  or  tension.  The 
sensation  is  proportional  to  the  work  T,  by  means  of  which 
the  change  of  the  inner  oscillatory  state  and  of  the  position 
of  the  parts  takes  place;  and  this  work  T is  to  be  deter- 
mined in  the  same  manner  as,  for  example,  in  the  isothermal 
change  of  pressure  and  volume  of  a gas.  According  to 
which  we  have 

7 P' 

7 = c .log 
y V 

where  c is  a constant.  Delboeuf  considered  Fechner’s  con- 
ception of  a negative  sensation  as  particularly  contradic- 

1 Theorie  de  la  sensibilite,  Bruxelles,  1876;  “La  loi  psychophysique, 
Hering  contre  Fechner,”  Revue  philosophique,  1877,  pp.  225  ff. 


250 


HISTORY  OF  PSYCHOLOGY 


tory.  Such  a negative  sensation  is  absolutely  impossible, 
since  a sensation  must  necessarily  be  something.  Delboeuf’s 
own  formulae  were  all  very  carefully  constructed,  so  that  no 
negative  sensation  values  might  be  deduced  from  them. 

The  difficulties  arising  out  of  the  concept  of  negative 
sensations  form  the  chief  argument  of  Langer1  against 
Fechner’s  law.  Negative  sensation  values  must  certainly 
be,  according  to  Langer,  such  that,  when  added  to  equally 
large  positive  values,  they  will  give  the  value  0.  Suppose 
we  have  two  finite  stimuli,  one  of  which  produces  the  sen- 
sation 7,  and  the  other  the  sensation  —7  below  the  thresh- 
old; then,  if  both  act  at  the  same  time,  the  sensation  0 
must  result.  Since  this  is  known  not  to  happen  in  expe- 
rience, Langer  thought  that  sensations  below  the  threshold 
should  be  called  “small  sensations,”  which,  because  of  their 
slight  intensity,  are  not  able  to  rise  to  consciousness.  The 
stimulus-threshold  would  then  become  a sensation-thresh- 
old, and  thus  the  difficulty  would  be  solved  in  a manner 
similar  to  Wundt’s  solution.2 

The  most  numerous  attacks  on  Fechner’s  law  were  due 
to  Hering.3  Weber’s  Law,  he  contends,  is  not  a correct 
deduction  from  the  experiments;  for  these  latter  merely 
prove  that  the  difference  in  sensation  remains  always  just 
noticeable  with  constancy  of  the  relative  difference  in 
stimulus.  It  is  quite  arbitrary  to  assume  that  with  dif- 
ferent degrees  of  stimulus  the  just-noticeable  difference  in 
sensation  is  the  same.  A second  difficulty  lies  in  the  con- 
siderable empirical  deviations  from  Weber’s  Law;  as  long 
as  these  deviations  cannot  be  explained  as  arising  from  the 
peculiarities  of  the  sense-organs,  nor  yet  the  necessity  of  the 
law  theoretically  proved,  then  Weber’s  Law  must  be  con- 

1 Grundlagen  der  PsychophysiJc,  eine  kritische  Untersuchung,  1876. 

2 See  below,  pp.  262  ff. 

3 “ fiber  Fechners  psychologisches  Gesetz,”  Wien.  Sitzungsber.,  Bd. 
LXXII,  1875. 


PSYCHICAL  MEASUREMENT 


251 


sidered  as  a very  uncertain  hypothesis.1  The  teleological 
consequences  also  lead  astray.  For  example,  the  percep- 
tion of  the  relation  of  two  extensive  or  intensive  values,  /3 
and  /3',  must  change  if  both  of  these  change  even  in  the 
same  relationship.  How  could  the  mind  correctly  perceive 
the  relations  of  the  outer  world  if  no  proportion  existed 
between  the  occurrences  of  the  outer  world  and  those  of 
our  inner  world?  This  objection  seems  to  be  particularly 
striking  and  seems  to  apply  well  to  extensive  psychical  values; 
a line  twice  as  long  as  another  is,  as  a rule,  seen  twice  as 
long.  Along  with  this  Hering  brought  forward  the  still  more 
general  a 'priori  objection  that  between  physical  and  psychi- 
cal processes  there  exists  an  immediate  dependence  upon  each 
other  which  is  at  once  recognized  as  a dependence  due  to 
cause  and  effect;  while,  on  the  other  hand,  a complicated 
law  of  these  relations  is  very  difficult  to  understand. 

As  an  experimental  counter-proof  against  Fechner’s  law, 
Hering  brought  forward  his  own  experiments  with  weights, 
in  which  he  investigated  the  comparing  of  more-than-no- 
ticeable  differences.2  If  to  one  galvanic  plate  lying  on  the 
hand  another  plate  is  added,  this  addition  appears  smaller 
than  if  five  plates  are  added  to  five  lying  on  the  hand. 
Experiments  of  this  kind  were  of  great  importance  because 
they  tested  at  first  hand  in  experience  the  generalization 
contained  in  Fechner’s  law.  Their  results  seemed  to  show 
that  more-than-noticeable  differences  are  by  no  means 
judged  as  equal  when  they  retain  the  same  ratio  to  the 
beginning  or  normal  stimulus,  but  that  they  are  judged  the 
same  when  they  are  absolutely  and  not  relatively  equal. 

Much  smaller  is  the  number  of  those  psychologists  who 
accepted  Fechner’s  formulae  without  making  any  change 
or  who  brought  forward  new  points  of  view  to  justify 
Weber’s  Law.  To  the  latter  belongs  J.  J.  Muller  with  his 
1 Op.  dt.,  p.  38. 


2 Op.  cit.,  pp.  14  ff. 


252 


HISTORY  OF  PSYCHOLOGY 


attempt  to  substantiate  the  usefulness  of  Fechner’s  funda- 
mental law.1  He  started  with  the  assumption  that  even 
with  a constant  stimulus  there  took  place,  because  of  the 
oscillations  of  the  nervous  excitability,  a continual  change 
in  the  sensation  which  might  just  as  well  be  produced  by 
a changing  stimulus  with  a constant  nervous  excitability. 
In  order  to  be  able  to  differentiate  subjectively  these  two 
kinds  of  changes  in  sensation  from  each  other,  the  sensation 
difference  caused  by  the  variation  of  the  stimulus  must  be 
independent  of  the  nervous  excitability  and  the  sensation 
difference  caused  by  the  variation  of  the  excitability  must 
be  independent  of  the  stimulus.  Muller,  assuming  that  the 
nervous  process  is  proportional  to  the  intensity  of  the  stim- 
ulus and  the  nervous  excitability,  proved  that  the  above 
demand  could  be  satisfied  only  if  the  sensation  increases 
proportionally  to  the  logarithm  of  the  nervous  process. 

(b)  Feclmer’s  Reply 

Fechner  answers  all  these  objections  with  a counter- 
criticism2 which  in  the  most  important  questions  retained 
the  same  point  of  view  as  laid  down  in  the  Elemente.  Only 
in  a few  special  empirical  points  does  he  admit  modification 
or  limitation,  as,  for  example,  when  he  says  that  Weber’s 
Law  taken  in  a generalized  form  can  be  applied  with  assur- 
ance only  to  differences  in  the  intensity  of  sensations.  On 
the  other  hand,  the  fundamental  interpretation  of  this  law, 
wdiich  is  made  firmer  by  being  transferred  from  outer  to 
inner  psychophysics,  remains  absolutely  untouched.  The 
inner  psychophysical  activity  is  proportional  to  the  stim- 
ulus, but  the  sensation  depends  logarithmically  upon  this 
activity.  The  empirical  deviations,  which  cannot  be  denied, 

1 Sitzungsber.  d.  Konigl.  Sachs.  Ges.  d.  Wissensch.,  math.-phys.  Kl., 
1870,  pp.  328  ff. 

2 In  Sachen  der  Psychophysik,  1877. 


PSYCHICAL  MEASUREMENT 


253 


do  not  rest  upon  any  contradiction  of  this  logarithmic  reg- 
ularity but  rather  upon  a disturbance  of  the  ratio  exist- 
ing between  the  psychophysical  activity  and  the  stimulus. 
In  regard  to  the  objection  first  raised  by  Mach,  which  he 
called  the  a 'priori  objection,  he  tried  to  prove  that  with  a 
simultaneous  dependence,  such  as  exists  between  psychical 
and  physical  stimuli,  the  simple  ratio  possesses  only  a small 
degree  of  probability.1  Body  and  soul  are  like  the  inner  and 
outer  modes  of  appearance  of  the  same  being.  If,  for  ex- 
ample, we  take  a circle  and  in  the  middle  of  this  or  at  any 
point  inside  it  suppose  an  eye  that  can  see  in  all  directions, 
and  outside  of  it  another  such  eye,  then,  speaking  generally, 
in  looking  at  the  circumference  the  same  parts  of  this  cir- 
cumference will  be  seen  at  different  angles  and  therefore 
appear  different  as  to  size.  And  these  different  sizes  do  not 
change  by  any  means  in  a constant  ratio.2  Against  this  idea 
of  proportion,  Fechner  brings  as  a special  argument  the 
fact  of  the  threshold.  According  to  the  law  of  proportion, 
the  weakest  psychophysical  process  ought  to  call  a sensa- 
tion into  existence.  If  the  concept  of  the  inner  threshold 
is  abandoned,  the  whole  psychophysical  interpretation  of  the 
relation  between  conscious  and  unconscious  mental  life  must 
be  abandoned  too.  Fechner’s  criticism  of  Delboeuf’ s “ con- 
trary sensations”  was  fully  as  keen  and  severe  as  the  latter’s 
criticism  of  Fechner’s  negative  sensations.  In  it  we  see  the 
philosophical  strain  that  runs  through  all  Fechner’s  thinking. 
The  mediation  between  outer  and  inner  psychophysics,  made 
possible  by  the  fundamental  psychophysical  formula,  is  the 
object  for  the  sake  of  which  Fechner  adheres  firmly  to  his 
original  interpretation  of  the  law. 

In  this  storm  of  criticism  the  obvious  contradictions  among 
Fechner’s  opponents  themselves  speak  strongly  in  Fechner’s 
favor,  so  that  he  was  able  to  say  at  the  end : “ The  tower  of 
1 Op.  cit.,  pp.  65  ff.  2 Op.  cit.,  pp.  67  /. 


254 


HISTORY  OF  PSYCHOLOGY 


Babylon  was  not  completed  because  the  workmen  could  not 
understand  each  other  as  to  how  they  should  build,  but 
my  psychophysical  foundation  must  remain  because  the 
workmen  could  not  come  to  any  agreement  as  to  how  they 
should  tear  it  down.”  1 

(c)  Some  Philosophical  Opponents 

Against  Fechner’s  fundamental  ideas  some  purely  phil- 
osophical attacks  were  directed.  These  form  merely  an 
interlude  in  the  real  controversy  over  Fechner’s  psycho- 
physics, for  this  was  ultimately  to  be  decided  on  the  ground 
of  psychological  experience  alone. 

F.  A.  Miiller2  characterized  all  investigations  that  set 
out  to  find  some  functional  relation  between  the  physical 
and  the  psychical  as  absolutely  hopeless.  Now,  the  func- 
tional relation  between  the  size  of  a sensation  and  the  size 
of  a stimulus,  both  determined  by  means  of  a certain  unit 
of  measurement,  is  exactly  what  the  axiom  of  psychophysics 
is  trying  to  represent.  The  supposed  difference  sensations  of 
Fechner  are  nothing  else  than  contrast-feelings  of  varying 
character.  Muller,  therefore,  looked  for  the  real  interpre- 
tation of  Weber’s  Law  in  the  field  of  psychology  and  thereby 
accepted  the  opinion  of  Wundt. 

The  so-called  “difference”  opinion  of  sensation  took  the 
chief  place  in  the  controversy  between  Fechner  and  Ulrici. 
It  has  very  often  been  supposed  that  a sensation  can  only 
arise  in  connection  with  or  as  a difference  from  another 
which  still  exists  or  has  existed  previously.  In  this  sense 
Schneider3  maintained  that  the  sensations  are  not  con- 
ditioned by  the  separate  nervous  excitations  as  such  but 

1 Op.  cit.,  p.  215. 

2 Das  Axiom  der  Psychophysik  und  die  Weberschen  Versuche,  1882. 

3 Die  Unterscheidung,  Analyse,  Entstehung  und  Entwicklung  ders., 
u.s.f.,  1877,  p.  3. 


PSYCHICAL  MEASUREMENT 


255 


by  the  differences  of  the  nervous  excitations.  In  favor  of 
this  “difference”  opinion,  Ulrici1  pointed  to  the  fact  that 
very  slightly  saturated  colors  could  only  be  recognized  by 
a comparison  with  a pure  gray.  Later  on,  in  connection 
with  some  criticism  of  Fechner’s,  he  came  to  the  conclusion 
that  in  addition  to  the  psychophysical  process  forming  the 
basis  for  a sensation  there  must  be  added  a special  act  of 
differentiation.2  But  this  act  belongs  to  a mental  field  su- 
perior to  the  field  of  sensation,  a field  in  which  we  cannot 
conceive  of  any  psychophysical  correlates.  Now,  since  the 
real  phenomena  of  consciousness  take  place  in  this  mental 
field,  any  inner  psychophysics  becomes  impossible. 

The  measurability  of  psychical  processes  upheld  by  Fech- 
ner  was  questioned  by  the  famous  historian  of  philosophy 
E.  Zeller,3  although  not  with  a very  happy  argument. 
The  latter  complained  of  the  lack  of  a unit  of  measure- 
ment applicable  to  all  cases,  in  order  to  denote  the  abso- 
lute size  of  a sensation.  The  just-noticeable  sensation 
which,  according  to  Fechner,  would  serve  this  purpose  was 
considered  by  Zeller  to  be  of  no  use  in  this  case.  Now 
Fechner  could  use  for  such  a unit  of  measurement  any  psy- 
chical value  which  corresponded  to  a stimulus  which  tran- 
scended its  threshold  value  in  a given  ratio.  Obviously, 
this  objection  of  Zeller  questioned  nothing  more  than  the 
absolute  measurability  of  sensations,  the  impossibility  of 
which  Fechner  had  from  the  very  beginning  acknowledged. 

Unquestionably,  the  most  important  of  those  opponents 
whom  Fechner  himself  called  his  philosophical  opponents 
was  the  physiologist  J.  v.  Rries.4  The  measurement  of 
a value  takes  for  granted  that  determinations  of  equality 
between  similar  elements  can  be  carried  out,  as  in  the  phys- 

1 Leib  und  Seele,  p.  294. 

2 Zeitschr.  f.  Philos,  u.  phil.  Kritik,  Bd.  LXXII,  p.  281. 

3 “ fiber  die  Messung  psychischer  Vorgange,”  Abh.d.  Berl.  Akad.,  1881. 

4 Vierteljahrsschr.  f.  wissensch.  Philos.,  VI,  1882,  pp.  257  ff. 


256 


HISTORY  OF  PSYCHOLOGY 


ical  universe,  with  space,  time,  and  volume.  The  measure- 
ment number  then  denotes  a multiple  of  the  same  thing. 
In  the  physical  world  intensive  values  are  measured  by 
reducing  them  by  means  of  definite  principles  to  spatial 
and  temporal  values.  These  conditions  of  measurability 
are,  however,  not  fulfilled  in  the  case  of  psychical  values. 
Let  us  first  of  all  suppose  that  the  whole  nervous  system  was 
unchangeable,  so  that  one  and  the  same  sensation  always 
corresponded  to  one  and  the  same  stimulus.1  Let  Ei,  Ez,  Ez 
be  the  sensations  corresponding  to  the  stimuli  Ri,  Rz,  Rz. 
In  carrying  out  any  experiment  for  purposes  of  measure- 
ment we  must  answer  the  question  as  to  whether  the  con- 
tention is  justifiable  that  the  change  of  sensation  from  Ei 
to  E2  is  equal  to  any  other,  say,  from  Ek  to  Ei,  or,  what 
comes  to  the  same  thing,  that  the  sensation  Em  is  so  many 
times  greater  than  the  sensation  En.  Unprejudiced  consider- 
ation will  show  at  once  that  such  a statement  can  have  no 
sense.  Intensive  values  are  not  in  themselves  measurable 
because  to  consider  equal  the  different  steps  of  an  intensity 
series  has  in  itself  no  definite  meaning.  The  contention 
that  the  addition  of  sensation  caused  by  placing  a two  and 
then  a three  pound  weight  on  a certain  part  of  the  skin  is 
equal  to  the  placing  of  a ten  and  then  a fifteen  pound  weight 
has  just  as  much  sense  as  if  we  were  to  say  that  a light 
vibration  is  equal  to  an  auditory  vibration.  The  apparent 
psychical  judgment  depends  in  reality  upon  our  compre- 
hension of  physical  values.  Hering  had  also  shown  that 
we  judge  weights  according  to  their  physical  measure  and 
not  according  to  any  logarithmic  principle;  in  the  field  of 
visual  sensations  the  same  was  shown  in  Delboeuf’s  ex- 
periments and  also  in  the  astronomical  determinations  of 
stellar  magnitudes. 

With  such  considerations  von  Kries  tried  to  show  the  im- 
1 Op.  ait.,  p.  273. 


PSYCHICAL  MEASUREMENT 


257 


possibility  of  all  psychophysics,  and  Fechner  himself  saw 
in  this  a fundamental  objection  to  which  one  only  needed 
to  consent  in  order  to  get  rid,  once  and  for  all,  of  the  whole 
mass  of  psychophysical  nonsense  which  had  accumulated.1 
The  new  foundation  of  the  theory  of  psychical  measurement, 
which  stands  in  close  connection  with  the  varying  interpre- 
tations of  Weber’s  Law,  is,  in  any  case,  of  more  importance 
for  the  determination  of  the  fate  of  Fechner’s  psychophys- 
ics than  the  settlement  of  those  questions  of  principle  which 
have  not  been  decided  up  to  the  present. 

4.  The  New  Foundation  of  Psychical  Measurement 

Out  of  the  controversy  over  Fechner’s  psychophysics, 
which  is  the  principal  feature  of  the  psychology  of  the 
sixties  and  seventies  of  the  last  century,  arose  various 
attempts  at  a new  foundation  of  psychical  measurement. 
G.  E.  Muller,  in  his  Grundlegung  der  Psychophysik,  took  up 
a position  which  was  opposed  to  Fechner  in  its  chief  points, 
whereas  Wundt  took  what  he  considered  tenable  in  the  old 
psychophysics  of  Fechner  and  incorporated  it  into  his  phys- 
iological psychology.  The  psychological  interpretation  of 
Weber’s  Law  as  formulated  by  Wundt  has  also  taken  on 
many  different  forms,  and  has  in  part  been  the  starting- 
point  for  the  most  recent  experimental  investigations. 


(a)  G.  E.  Muller’s  Foundation  of  Psychophysics 

The  investigation  of  Muller,  appearing  under  the  title 
Grundlegung  der  Psychophysik,  in  the  year  1878,  was  almost 
entirely  devoted  to  Weber’s  Law.  Because  of  its  com- 
pleteness and  the  acuteness  of  its  criticism  it  has  become 
a landmark  in  the  history  of  psychophysics.  From  a crit- 
1 Revision,  p.  324. 


258 


HISTORY  OF  PSYCHOLOGY 


ical  survey  of  the  facts  of  Weber’s  Law  it  appeared  that  it 
is  valid  with  any  degree  of  certainty  only  for  the  senses 
of  vision  and  audition  and  the  muscle  sense,  and  that  only 
within  definite  limits.  It  is,  therefore,  not  correct  to  speak 
of  upper  and  lower  deviations,  for  it  is  rather  the  general 
rule  that  the  relative  difference  sensitivity  changes  with 
the  intensity  of  the  stimulus.  Within  those  limits  where 
Weber’s  Law  seems  to  be  valid  these  changes  are  so  small 
and  occur  so  slowly  that  they  can  be  neglected  for  all  prac- 
tical purposes. 

But  even  within  this  region  of  validity  Fechner’s  formula 
of  measurement  cannot  be  retained.  Weber’s  Law  merely 
says  that  the  just-noticeable  difference  of  two  sensations 
s'  and  s"  remains  constant  to  the  ratio  of  the  stimuli,  that  is, 


Fechner’s  formula  of  measurement,  s = k .log  where  k 

is  a constant  and  p the  stimulus-threshold,  does  not  take 
into  account  the  upper  and  lower  deviations.  Now,  if  under 
the  supposition  of  equal  values  of  equally  noticeable  addi- 
tions of  sensation  the  formula  s = cj>  (f)  can  be  deduced  from 
the  actual  behavior  of  the  value  of  the  difference-threshold, 

*(»■) 

then  there  follows  at  once,  by  putting  e * = 9 (r),  the 
corrected  formula  of  measurement: 

s = tc  log  $ (r), 

and  out  of  this,  by  differentiation,  the  corrected  fundamen- 
tal formula: 

ds  = K ‘ ^ • dr 

</>  (r) 

The  function  4>  (r)  is,  in  accordance  with  the  upper  and 
lower  deviations,  convex  toward  the  axis  of  the  curve  for 


PSYCHICAL  MEASUREMENT 


259 


small  values  of  r;  and  as  r increases  it  approximates  to  a 
straight  line  and  then  becomes  concave  toward  the  axis. 
The  turning-point  lies  at  the  maximum  of  the  relative  dif- 
ference sensitivity. 

For  the  interpretation  of  the  validity  of  such  a formula 
of  measurement  Muller  admitted  two  alternatives.  Either 
the  sensation  intensity  s is  proportional  to  the  psycho- 
physical activity  E,  and  this  latter  increases  within  certain 
limits  almost  like  the  logarithm  of  the  stimulus  r,  or,  con- 
versely, there  exists  approximate  proportionality  between  the 
two  last  processes,  so  that  the  sensation  intensity  increases 
in  arithmetical  progression,  while  the  psychophysical  ac- 
tivity increases  in  geometrical  progression.  According  to 
the  first  view, 

s = k"E, 

and  for  the  nervous  excitation  E (psychophysical  activity) 
we  have  the  equation 

E = k'  log  $ (r), 

which  Muller  called  the  formula  for  the  measurement  of 
nervous  excitation.  According  to  the  second  view, 


and 


s = k .log  E 
E — (r) 


are  the  expressions  for  Fechner’s  psychophysical  law. 

The  first  view  leads  to  a physiological  interpretation  of 
Weber’s  Law,  and  Muller  emphatically  supported  such  an 
interpretation  as  against  the  psychophysical  one.  First  of 
all,  a logarithmic  relation  between  two  physical  states  is 
easily  thinkable.  The  difference,  for  example,  in  height  above 
sea-level  of  two  towns,  where  the  barometer  is  B and  b 


B 

respectively,  is  equal  to  C . log  — , where  C is  a constant 

o 


260 


HISTORY  OF  PSYCHOLOGY 


dependent  upon  various  circumstances.  And  the  stimulus- 
threshold  can  easily  be  explained  because  of  physiological 
inhibition. 

Muller  also  directed  his  criticisms  against  the  psycho- 
logical interpretation  of  Weber’s  Law.  According  to  this  in- 
terpretation two  sensations,  in  order  to  appear  to  us  dif- 
ferent in  a constantly  noticeable  manner,  must  not  show  a 
constant  difference  to  each  other  but  rather  must  form  a 
constant  ratio.  This  leads  to  the  equation: 


V (r) 
<f>  (r) 


dr, 


where  p is  a constant.  The  same  equation  can  be  deduced 
from  s = ic  . (</>  (r)  )p . In  this  manner  he  opposed  the  psycho- 
logical point  of  view  held  by  Plateau,  Brentano,  and  others. 

Hering’s  standpoint  is,  according  to  Muller,  just  as  un- 
tenable. In  his  experiments  with  weights  he  ought  not  to 
have  taken  as  his  question  whether  two  weights  of  1,000 
and  2,000  grammes  appear  to  differ  by  the  same  amount  of 
weight  as  two  weights  of  100  and  200  grammes  respectively. 
He  ought  to  have  raised  the  real  psychological  question 
as  to  whether  the  two  former  produce  an  equally  noticeable 
difference  in  sensation  as  do  the  two  latter.  We  do  not 
perceive  the  differences  or  relations  of  given  sensations  but 
only  the  noticeability  of  these  differences  and  relations,  and 
we  judge  these  latter  as  to  equality  or  difference.  What 
difference  in  weight  or  what  relation  of  weights  we  conceive 
as  the  outer  cause  of  a difference  of  two  weight  sensations 
noticeable  to  any  degree  depends  entirely  upon  our  ex- 
perience. And  this  makes  invalid  Hering’s  objection  that 
the  absence  of  any  proportion  between  sensation  and  size  of 
weight  would  make  impossible  the  acquisition  by  practice 
of  mechanical  skill;  this  learning  rests  upon  associations 
formed  between  weight  sensations  and  the  ideas  of  the 


PSYCHICAL  MEASUREMENT 


261 


amount  of  strength  to  be  exerted.  This  substitution  of  the 
noticeability  of  sensations  in  place  of  the  conception  of  their 
size  stands  the  test  of  any  further  arguments  of  Hering.  The 
latter  might  contend  that  if  the  size  of  a sensation  corre- 
sponding to  the  length  of  a given  line  were  to  increase  slower 
than  the  line,  then  two  triangles  geometrically  similar  but  of 
different  sizes  would  have  to  appear  to  us  as  dissimilar,  since 
the  relation  of  the  three  sides  in  each  of  the  triangles  would 
be  quite  different.  To  all  of  which  Muller  would  reply  that 
in  such  a case  the  differences  in  the  lengths  of  the  sides  would 
appear  equal  precisely  in  accordance  with  Weber’s  Law. 

Muller’s  criticism  was  directed  against  all  other  concep- 
tions of  psychophysics,  in  so  far  as  he  sought  to  show  the 
untenability  of  the  psychophysical  view,  as  well  as  of  all  non- 
physiological  theories.  It  was  in  the  main  this  keen  and 
radical  attack  that  led  Fechner  to  subject  the  principal  prob- 
lems of  psychophysics  to  a revision.1  If  the  criticism  of  Muller 
was  valid,  then  psychophysics  was  nothing  but  an  historical 
relic;  and  so  he  once  more  set  himself  to  meet  all  attacks  with 
the  picturesque  and  proud  statement  that  a post  by  being 
shaken  becomes  looser  and  looser,  but  a tree,  if  it  is  not 
torn  down,  will  only  thereby  root  itself  more  firmly  in  the 
ground.2  Fechner  outlined  clearly  and  sharply  the  physi- 
ological and  the  psychophysical  points  of  view  between 
which  it  seemed  to  him  a decision  must  be  made.  Out  of 
the  well-known  formulae  there  follows  for  the  latter  a stim- 
ulus-threshold, whereas  for  the  former  there  is  none.  Ac- 
cording to  the  psychophysical  point  of  view  Weber’s  Law 
is  fundamental,  but  according  to  the  physiological  point  of 
view  it  has  no  validity  for  inner  psychophysics.  If  this 
latter  is  true  there  can  be  no  physical  principle  by  means 
of  which  the  relation  of  the  intensities  of  two  physical 

1 Revision  der  Hauptprobleme  der  Psychophysik,  1882. 

2 Op.  cit.,  Vorrede,  p.  5. 


262 


HISTORY  OF  PSYCHOLOGY 


T 

processes  - can  be  translated  into  a difference  of  the  suc- 
r 

ceeding  dependent  processes  E'  — E in  such  a manner  that 
/ 

T 

to  n times  - would  correspond  n times  the  difference  of 

E'—E.  The  physiological  examples  of  Muller  and  others 
only  show  the  dependence  of  end  result  (e.  g.,  the  height  of 
the  pull  of  a muscle)  upon  the  exciting  stimulus  but  not 
the  real  dependence  between  two  processes  in  motion,  with 
which  psychophysics  is  alone  concerned.  The  fact  of  the 
inner  threshold  cannot  be  explained  by  means  of  resistance 
in  the  conductivity  of  the  central  substance,  because  the 
inhibition  follows  according  to  the  principle  of  relative 
weakening  and  so  can  never  die  out.  Again,  the  non- 
contradictory  mathematical  correlation  of  a whole  system 
of  formulae  supports  the  psychophysical  view-point.  And, 
lastly,  the  conception  of  the  whole  physical  process  of  the 
universe  as  a psychophysical  one  necessarily  presupposes 
a psychophysical  interpretation  of  the  formulae  of  measure- 
ment. 

We  see  again  in  all  this  how  Fechner’s  whole  thinking, 
rooted  as  it  is  in  profound  but  fantastic  conceptions,  can 
never  be  reconciled  with  the  demands  of  purely  empirical 
thought.  In  the  meantime,  however,  there  sprang  up  a 
third  interpretation  of  Weber’s  Law — the  psychological  in- 
terpretation. 

( b ) The  Psychological  Interpretation  of  Weber’s  Law 

The  psychological  interpretation  of  Weber’s  Law  ap- 
pears with  constantly  increasing  clearness  in  the  thought 
of  Wundt.  Even  in  1863,  in  his  Lectures  on  Human  and 
Animal  Psychology,  he  was  striving  toward  a psychological 
conception  of  Weber’s  Law.  He  pointed  to  the  meaning  of 
the  act  of  comparison  and  saw  in  our  relative  judgment 


PSYCHICAL  MEASUREMENT 


263 


a proof  of  the  purely  psychological  nature  of  this  law.1 
Weber’s  Law  cannot  be  deduced  either  from  the  physiological 
peculiarities  of  the  nervous  substance  or  from  a functional 
relationship  between  the  physical  and  the  psychical,  for  it 
is  founded  in  the  psychical  processes  which  are  at  work  in 
the  comparison  of  sensations.  It  is  in  this  sense  not  a law 
of  sensation  but  a law  of  apperception.  Even  though  in 
the  first  edition  of  his  Principles  of  Physiological  Psychology 
(1874)  the  logarithmic  equation  set  up  by  Weber’s  Law  was 
taken  to  represent  the  dependence  of  the  sensation  upon 
the  physiological  process,  yet  later  this  mathematical  rela- 
tionship was  conceived  as  one  between  purely  psychical 
factors.  In  this  way  Fechner’s  formula  of  measurement 
could  be  brought  into  a form  in  which  it  contained  only 
homogeneous  terms.  So  that  now  sensation  and  stimulus 
do  not  enter  into  any  functional  relationship,  but  the  law 
only  tells  us  how  the  degree  of  noticeability  of  a sensation 
changes  with  the  intensity  of  the  sensation.  If  we  denote  a 
constant  degree  of  noticeability  by  k,  and  the  change  in 
the  sensation  intensity  corresponding  to  it  by  A E,  then 

7 A E 

k = c"E 

is  the  empirical  expression  for  the  observed  facts.  The 
growth  of  the  sensation  E must,  then,  be  assumed  to  be 
proportional  to  the  stimulus.  Following  this  interpreta- 
tion, we  have  in  Wundt’s  survey  of  the  position  his  attempt 
to  explain  the  physiological  processes  by  means  of  a hypo- 
thetical apperception  centre.  His  analysis  of  the  inhibition 
processes  which  occur  in  this  centre  during  the  conduction 
of  nervous  processes  is  an  example  of  a psychophysical 
analysis  of  complex  cerebral  functions  which  is  intended 
to  show  that  the  psychological  interpretation  need  by  no 
1 Op.  cit.,  I,  pp.  133  /.  Cf.  also  above,  p.  134. 


• 264 


HISTORY  OF  PSYCHOLOGY 


means  come  into  contradiction  with  our  knowledge  of  phys- 
iological nervous  conductivity. 

In  just  as  decided  a manner  did  Theodor  Lipps,1  who  at 
first  started  with  a psychophysical  interpretation,  advance 
toward  a psychological  interpretation,  in  which  the  growth 
of  sensations  is  proportional  to  the  growth  of  stimuli,  and 
the  facts  of  Weber’s  Law  are  deduced  from  the  universal  and 
fundamental  psychological  law  of  the  relative  quantitative 
identity  of  the  elements  of  a whole.2  The  total  quantity 
appears  reduced  in  proportion  to  its  undividedness.  For 
the  manner  of  this  reduction  we  can  get  the  following  for- 
mula: If  component  parts  already  present  (m)  are  increased 
by  new  homogeneous  parts,  then  the  psychical  quantity  of 
the  increase  undergoes  such  a reduction  that  we  can  put 

n 

for  the  increase  in  quantity  the  formula  — . C,  where 

m + n 

C is  a constant.  This  formula  expresses  immediately  the 
law  of  relativity,  according  to  which  a whole,  in  regard  to 
its  power  of  making  an  impression,  appears  to  be  increased 
in  an  equal  manner  if  it  undergoes  an  increase  that  is  rela- 
tively equally  large.3  In  this  manner  the  size  of  the  im- 
pression is  determined  by  a purely  psychomechanical  process. 
If,  however,  equal  and  absolute  differences  in  stimuli  are 
found  with  the  help  of  the  gradation  method,  on  the  ground 
of  a judgment  of  supraliminal  differences,  then  there  must 
occur  an  apperceptive  division  of  the  whole,  according  to 
which  the  absolute  increases  play  their  part  without  any 
reduction. 

1 Grundtatsachen  des  Seelenlebens,  1883,  pp.  75  /.  “ Die  Quantitat  in 
psychischen  Gesamtvorgangen,”  Sitzungsber.  d.  philos. -philol.  u.  d.  hist. 
Kl.  d.  Kgl.  Bayr.  Akad.  d.  Wissensch.,  1899,  III,  pp.  400  ff. 

2 “Das  Relativitatsgesetz  der  psychischen  Quantitat  und  das  We- 
bersche  Gesetz,”  op.  tit.,  1902,  I,  pp.  1 ff.  Cf.  also  W.  Wirth,  Arch, 
f.  d.  ges.  Psych.,  Bd.  XIV,  1909,  pp.  217  ff. 

3 Psychologische  Studien,  2 Aufl.,  1905,  p.  253. 


PSYCHICAL  MEASUREMENT 


265 


In  this  way  Lipps  approaches  Wundt  very  closely  in  his 
assumption  of  a difference  in  the  manner  of  judging  just- 
noticeable  and  more-than-just-noticeable  differences.  In 
spite  of  this,  the  difference  remains  that  Lipps  asserts  the 
ratio  between  the  stimuli  and  the  unconscious  psychical 
processes  and  not  between  the  stimuli  and  the  sensation  in- 
tensities, i.  e.,  simple  contents  of  consciousness.  In  accor- 
dance with  this,  in  explaining  absolute  judgment  he  has  re- 
course again  to  the  unconscious  processes.  A division  into 
parts  of  a content  of  consciousness  is  altogether  meaning- 
less, but  we  can  conceive  of  such  a division  in  regard  to 
unconscious  real  processes. 

Among  the  other  opinions  that  approximate  to  the  psy- 
chological interpretation  we  find  the  one  of  G.  Heymans,1 
in  which  Weber’s  Law  is  subordinated  to  the  more  gen- 
eral phenomenon  of  psychical  inhibition.  He  observed  that 
qualitatively  similar  but  locally  different  sensations  tended 
to  crowd  each  other  out,  and  this  expressed  itself  as  an  in- 
hibition in  an  increase  of  the  stimulus  or  difference-threshold. 
Weak  sensations  are  crowded  out  of  consciousness  by  the 
stronger  ones  just  in  proportion  to  the  intensities  of  the 
latter.  An  extension  of  this  law  to  apply  to  the  weak  sen- 
sations of  difference  is  all  that  is  required  to  explain  the 
general  content  of  Weber’s  Law.  The  difference-threshold 
is  a case  of  inhibition  and  Weber’s  Law  is  a special  case, 
i.  e.,  a limiting  case  of  the  law  of  inhibition.  All  this  as- 
suredly calls  to  mind  the  Herbartian  principles  governing 
the  mechanism  of  ideas.  And  yet  what  a difference  be- 
tween the  old  and  imaginary  statics  and  mechanics  of 
ideas  and  this  new  theory  of  inhibition!  The  former  in- 
cluded the  whole  of  consciousness  but  this  only  a compara- 
tively small  group  of  psychical  phenomena.  In  the  former, 
brilliant  mathematical  speculation  into  the  unlimited  field 
1 Ztschr.  f.  Psych,  u.  Phys.,  Bd.  XXVI,  1901,  pp.  305  ff. 


266 


HISTORY  OF  PSYCHOLOGY 


of  the  possible  challenges  our  admiration;  in  the  latter,  we 
meet  the  more  modest  results  which  have  been  laboriously 
gleaned  from  the  field  of  experience. 

These  forms  of  the  psychological  interpretation  seemed 
also,  however,  to  be  subject  to  the  general  objections  which 
von  Ivries  had  previously  directed  against  Fechner’s  psy- 
chophysics.1 Meinong2  renewed  this  argument  in  the  fol- 
lowing form:  In  general,  equal  differences  may  cause  un- 
equal sensation  differences  and  equal  sensation  differences 
may  point  to  unequal  differences  in  stimulus.  The  dis- 
parity of  two  psychical  contents  corresponds  neither  with 
their  absolute  nor  with  their  relative  stimulus  difference 
and  can  only  be  brought  into  a close  relationship  with  the 
latter.  The  facts  of  Weber’s  Law  allow,  therefore,  of  no 
other  conclusion  than  this,  that  to  each  definite  value  of 
sensation  difference  there  corresponds  one  and  only  one 
value  of  the  relative  stimulus  difference,  and,  conversely, 
one  and  only  one  value  of  sensation  difference  corresponds 
to  each  value  of  the  relative  stimulus  difference.  In  the 
deduction  of  the  formula  of  measurement  the  formation 
of  the  difference  of  two  sensations  en—e  is  the  point  most 
open  to  attack.  Sensations  cannot  be  added  or  subtracted. 
And  if  the  separate  e is  conceived  of  as  a number  of  degrees 
of  noticeability  we  do  not  thereby  gain  any  information 
as  to  the  content  of  these  degrees. 

The  close  connection  which  Fechner  thought  to  exist 
between  the  principle  of  psychical  measurement  and  the 
psychophysical  interpretation  of  Weber’s  Law  has  been 
destroyed.  In  spite  of  all  the  polemics  against  Fechner,  it 
was  once  thought  that  psychology  would  achieve  its  object 
if  it  determined  the  validity  of  Weber’s  Law  in  every  de- 
partment; but  at  the  present  time  we  have  progressed  far 

1 Cf.  pp.  225  f.,  above. 

2 Ztschr.  f.  Psych,  u.  Phys.,  Bd.  XI,  1883,  pp.  81  ff.,  230  ff.,  353  ff. 


PSYCHICAL  MEASUREMENT 


267 


beyond  this  one-sided  view.  The  inner  psychophysics  of 
Fechner,  which  led  to  a perfectly  transcendental  metaphysic 
of  consciousness,  has  long  ago  been  relinquished.  There  has 
been  retained,  however,  in  experimental  psychology,  the  con- 
cept of  psychical  measurement  and  with  it  the  task  of  ar- 
ranging a relation  based  upon  number  between  a mani- 
foldness of  correlated  psychical  elements  and  a field  of  outer 
processes.1 

1 Cf,  G,  F.  Lipps,  Grundriss  der  Psychophysik,  1903,  p.  40. 


PART  III 


A HISTORY  OF  THE  MOST  IMPORTANT 
PSYCHOLOGICAL  THEORIES 

CHAPTER  X 

THEORIES  OF  SENSATION 

If  psychology  feels  itself  called  upon  to  take  the  same 
fundamental  position  among  the  mental  sciences  as  physics 
has  taken  among  the  natural  sciences,  it  would  seem  perti- 
nent to  raise  the  question  as  to  whether  there  has  not  oc- 
curred in  the  history  of  psychological  theory  a reaction 
similar  to  the  one  which  occurred  in  the  history  of  physical 
theories  due  to  the  so-called  mechanical  conception  of  the 
universe.  What  a gulf  separates  modern  natural  science 
from  the  Aristotelian  physics  dominant  during  the  Middle 
Ages!  Not  only  do  changed  conceptions  lie  at  the  bottom 
of  present-day  theories,  but  the  fundamental  thought,  the 
reduction  of  all  phenomena  to  the  movement  processes  of 
the  smallest  parts,  has  become  a new  standard  for  all 
physical  theories.  In  psychology,  however,  we  do  not  no- 
tice any  such  radical  change  of  position  in  regard  to  the 
content  of  consciousness;  there  is  at  most  a suggestion  of 
this,1  and  even  then  in  a different  sense,  so  that  we  see  in 
the  history  of  psychological  theories  no  such  thoroughgoing 
reaction  as  we  do  in  the  case  of  the  natural  sciences. 

Nevertheless,  we  do  note  an  analogous  transformation 

1 See  pp.  43  and  209. 

268 


THEORIES  OF  SENSATION 


269 


in  some  departments,  as,  for  example,  in  sense-perception. 
The  more  modern  theories  of  sense-perception,  which  trace 
the  rise  of  percepts  out  of  elementary  processes,  excel  early 
attempts  at  an  explanation  of  perception  as  much  as  the 
mechanical  theory  of  heat  excels  the  earlier  theory  of  a heat 
material.  That  modern  psychology  offers  a more  exact 
basis  for  attempts  to  establish  a psychical  mechanics,  for- 
merly undertaken  in  a very  questionable  manner,  can  be 
seen  in  part  in  the  determination  of  psychophysical  con- 
stants. Each  of  the  more  modern  physical  theories  includes 
certain  kinds  of  physical  constants.  The  physics  of  Aris- 
totle explained  the  fall  of  a body  by  the  desire  of  the  body 
to  reach  its  natural  place,  the  centre  of  the  earth.  The 
theory  of  Galileo  about  a falling  body  led,  on  the  other  hand, 
to  the  determination  of  a physical  constant,  i.  e.,  gravity. 
It  is  possible  that  the  determination  of  psychophysical  con- 
stants, such  as  difference-thresholds,  reaction-times,  scopes 
of  consciousness,  etc.,  has  an  analogous  meaning  for  psycho- 
logical theories. 

Do  these  constants,  as  in  physics,  result  in  hypotheses? 
Without  doubt  there  are  hypotheses  in  psychology,  as, 
for  example,  those  about  the  physiological  processes  that 
underlie  psychical  phenomena;  in  this  sense  we  speak  of 
hypotheses  of  light  sensation  or  of  the  hypothetical  phys- 
iological processes  underlying  the  feelings.  The  analogy 
between  these  and  the  real  hypotheses  of  natural  science 
is,  however,  a loose  one.  The  ultimate  physical  theories, 
like  that  of  the  discontinuity  of  matter,  of  its  kinetic-elastic 
or  kinetic-electrical  composition,  contain  within  themselves 
presuppositions  as  to  the  substratum  into  which  the  phe- 
nomena are  to  be  transformed.  We  do  not  in  psychology, 
to  continue  the  same  examples,  transform  visual  sensations 
into  retinal  stimulations  or  feelings  into  changes  in  inner- 
vation. There  have  been,  it  is  true,  attempts  in  modern 


270 


HISTORY  OF  PSYCHOLOGY 


psychology  to  transform  the  content  of  consciousness  in 
the  same  empirical  manner  as  physics  has  done  with  its 
phenomena.1  But  in  the  history  of  psychology  any  such 
transformation,  which  must  necessarily  have  led  to  real 
psychological  hypotheses,  always  fell  within  the  scope  of 
metaphysics.  Such  hypotheses  are  excluded  from  pure  psy- 
chology because  a hypothetical  content  of  consciousness, 
the  existence  of  which  is  only  presupposed  and  not  proved, 
is  a concept  that  contradicts  the  phenomenological  point 
of  view.  Contents  of  consciousness  can  be  considered  hy- 
pothetical only  in  the  sense  that  we  do  not  perceive 
them  as  separated  and  isolated,  but  that  we  deduce  them 
from  their  effects;  an  example  of  such  is  the  part  certain 
difference  tones  of  a high  order  play  in  the  consonance 
theory  of  F.  Krueger.2  Such  a psychological  hypothesis 
does  not,  like  the  physical,  reach  over  into  another  sphere 
of  reality,  for  the  hypothetical  content  of  consciousness  is 
lacking  only  in  the  conditions  necessary  for  its  acceptance 
such  as  the  other  contents  of  consciousness  possess.  And 
with  this  is  closely  connected  the  fact  that  the  oppositions 
in  principle,  which  in  natural  science  are  first  met  with 
among  the  hypotheses,  are  in  psychology  to  be  observed  in 
the  separate  theories  themselves. 

By  far  the  greater  number  of  psychological  theories  are 
concerned  with  conscious  experiences  with  which  a so-called 
outer  experience  is  connected.  The  processes  of  sensation 
and  perception  have  from  the  very  beginning  challenged 
theoretical  explanation.  In  the  field  of  subjective  conscious 
states  the  theories  of  feeling  and  will  have  been  the  most 
important.  Within  the  theories  of  sensation  we  can  further 
distinguish  general  theories  and  theories  dealing  with  spe- 
cial sensations,  e.  g.,  vision  and  hearing. 

1 See  p.  209. 

2 Psych.  Stud.,  Bd.  V,  1910,  pp.  319  ff.  Cf.  below,  3 (d). 


THEORIES  OF  SENSATION 


271 


i.  General  Theories  of  Sensation 

The  distinction  between  sensation  and  perception  be- 
longs only  to  the  most  modern  concepts  of  psychology,  and 
accordingly  in  historical  development  theories  of  sensation 
correspond  entirely  with  those  of  perception.  And  yet  in 
the  historical  development  we  can  recognize  the  material 
distinction  between  the  processes  of  sensation  and  those  of 
perception.  The  theories  of  sensation  have  always  been 
dependent  upon  physiological  knowledge;  apart  from  iso- 
lated anticipations,  any  advance  of  the  former  has  been 
dependent  upon  the  growth  of  the  latter.  As  soon  as  the 
theories  of  sensation  became  freed  from  metaphysical  hy- 
potheses they  became  closely  affiliated  to  physiology.  The 
theoretical  utilization  of  the  purely  psychological  arrange- 
ment of  sensations,  e.  g.,  in  the  modern  theories  of  color 
sensations,  belongs  to  the  most  modern  development.  In 
the  theories  of  perception,  on  the  other  hand,  we  notice 
from  the  earliest  times  that  they  are  strongly  influenced  by 
definite  philosophical  theories.  Although  such  oppositions 
have  only  stood  out  the  more  clearly  because  of  the  clearer 
definition  of  terms  in  modern  times,  yet  we  can  trace  them 
back  in  their  broad  outlines  to  the  earliest  times. 

The  gradual  separation  between  theories  of  sensation  and 
theories  of  perception  was  in  part  prepared  for  by  the 
analogous  opposition  in  the  theory  of  primary  and  secon- 
dary qualities,  which  is  essentially  connected  with  the  name 
of  Locke,  even  though  it  possesses  a much  longer  prelim- 
inary history.1  As  primary  differences  Aristotle  recognized 
the  chief  oppositions  in  the  qualities  of  touch  sensation,  e.  g., 
warm  and  cold,  dry  and  wet.  In  the  philosophy  of  the 
Arabians  these  were  contrasted  as  primary  qualities  (qua- 
1 Cf.  Baeumker,  Arch.  /.  Gesch.  d.  Phil.,  XXI,  1908,  p.  492. 


272 


HISTORY  OF  PSYCHOLOGY 


litates  primes  or  primaries ) with  the  remaining  derivative 
qualities  of  sensation,  and  this  was  also  the  case  with  Al- 
bertus  Magnus  in  his  division  into  prima  sensibilia  and 
secunda  sensibilia.  In  the  fourteenth  century,  as  shown 
in  Heinrich  von  Hessen,  the  expression  qualitates  secundce 
gradually  came  to  be  adopted.  It  was,  however,  the  me- 
chanical theories  of  the  universe  that  revived  the  origi- 
nal Aristotelian  concept  of  common  contents  of  perception, 
such  as  size,  number,  and  movement.  Galileo  called  these 
the  first  accidents  in  contradistinction  to  the  purely  sub- 
jective qualities  of  sensation;  and  Robert  Boyle  used  the 
expression  “secondary  qualities”  for  the  purely  sensory 
qualities.  And  in  this  way  the  contrast  was  formed  for 
which  Locke  used  the  scholastic  terminology  of  primary 
and  secondary  qualities.  Although  since  that  time  the  dis- 
tinction between  sensation  and  perception  has  never  been 
lost,  yet  even  up  to  the  present  time  several  perceptions, 
e.  g.,  the  spatial,  have  been  classified  as  special  kinds  of 
sensations,  a thing  which  has  been  due  to  the  influence  of 
certain  theoretical  points  of  view,  as,  for  example,  of  na- 
tivistic  theories.  However  much  the  psychology  of  the 
senses  has  proved  itself  to  be  dependent  upon  physical  and 
physiological  knowledge,  yet  a psychological  interpretation 
and  utilization  of  the  discovery  of  the  physiological  con- 
ditions underlying  sensation  and  perception  has  very  often 
been  slow  in  appearing.  The  accommodation  of  the  eye  as 
a purely  physiological  fact  was  discovered  by  Kepler;  its 
importance  for  the  comprehension  of  depth  has  only  been 
appreciated  in  modern  theories.  In  the  same  way  the 
facts  of  color-mixture  were  known  for  a long  time  before 
attempts  were  made  to  explain  color  sensations  by  means 
of  an  analogous  stimulation  of  color  substances  in  the  eye. 

Among  the  general  theories  of  sensation  there  predom- 
inated in  earlier  times  fantastic  conceptions  of  the  origin 


THEORIES  OF  SENSATION 


273 


of  sensations.  Modern  physiology  was  the  first  to  bring 
forward  a principle  which  led  to  a general  theory  of  sensa- 
tion, namely,  the  principle  of  the  specific  energy  of  the 
nerves. 


(a)  The  Older  Theories 

Ancient  ideas  as  to  the  origin  of  sensation  were  confined 
within  the  circle  of  thought  dealing  with  metaphysical 
theories  of  the  soul.  At  the  beginning  of  his  treatise  on 
sensations,  Theophrastus  classifies  sensation  theories  into 
two  groups:  in  those  of  the  first  group  the  sensation  is  ex- 
plained by  the  working  of  similar  upon  similar  (™  6/j.ouo 
ha  T-qv  o/j-oioTrjTa) ; in  the  second  a working  of  opposite 
upon  opposite  is  presupposed  (t<w  evavrCcp  Sia  Trjv  aWoiacriv). 
The  famous  sensation  theory  of  Empedocles  shows  the 
three  component  parts  of  all  these  theories:  an  emanation 
of  small  particles  by  the  perceived  objects,  a special  forma- 
tion of  canals  in  the  sense-organs,  and  currents  flowing 
through  these  canals  to  the  outer  movements. 

In  the  sensation  theory  of  Aristotle  the  sensation  could 
be  nothing  else  than  the  transformation  of  a faculty  for 
sensation  into  reality.  Certainly  some  kind  of  a move- 
ment, or  in  general  some  kind  of  a change  (aAAoiWi?), 
forms  the  basis  of  a sensation;  but  the  sensation  is  not, 
therefore,  an  affection  of  the  soul.  For  the  movement  is 
carried  along  right  up  to  the  soul,  but  does  not  continue 
within  the  soul.1  Besides  this  the  soul  does  not  receive 
the  matter  of  the  object  but  only  the  form,  just  as  wax 
receives  the  form  of  a signet-ring.2  The  soul  actively 
reproduces  this  form  by  means  of  the  faculty  of  sensation. 
Besides  the  stimulus  the  sense-organ  exerts  some  kind  of 
activity  in  the  act  of  sensation.3  For  the  ability  of  the  eye 

1 De  somn.,  1.  2 De  anima,  II,  12.  3 De  gen.  an.,  V,  1. 


274 


HISTORY  OF  PSYCHOLOGY 


to  produce  changes  in  the  outer  world,  Aristotle  cites  the 
popular  belief  that  the  look  of  women  will  at  certain  times 
produce  spots  on  mirrors;  and,  in  hearing,  the  air  confined 
in  the  ear  is  supposed  to  imitate  the  sound  movement. 

The  Aristotelian  theory  of  sensation  underwent  trans- 
formation in  two  almost  opposite  directions.  In  Neo-Pla- 
tonic  psychology  we  find  in  Porphyry  the  thought  that  the 
soul  in  sensation  merely  recognizes  its  own  content.1  On 
the  other  hand,  the  Aristotelian  theory  was  reduced  to 
the  simpler  conception  as  typified  by  the  picture  theory. 
Even  in  the  Peripatetic  school  there  arose  the  theory  of 
species  sensibiles  or  intentionales,  fine  or  delicate  pictures, 
which  were  supposed  to  penetrate  through  the  hollow  nerves 
up  to  the  sensorium  commune.  There  existed  such  species 
not  only  for  the  simple  sensations  but  also  for  complex  ideas 
such  as  size  and  number,  and  this  very  questionable  theory 
was  held  in  great  regard  during  the  Scholastic  period. 

It  was  left  for  the  discoveries  of  the  modern  physiology 
of  the  nerves  and  the  opposition  to  the  influxus  physicus 
to  make  a change  in  the  theories  of  sensation.  In  accor- 
dance with  the  ideas  of  his  age,  Descartes  sought  to  make 
the  origin  of  sensation  intelligible  by  explaining  it  as  a 
movement  of  the  vital  spirits  rising  from  the  heart,  caused 
by  the  stimulation  conducted  along  the  nerves.  Even 
though  the  effect  of  the  vital  spirits  upon  the  soul  remained 
unexplained,  still  the  insight  that  sensation  and  its  object 
do  not  need  to  possess  any  similarity  was  an  important  step 
for  the  theory  of  sensation.2 

A more  important  modern  point  of  view  appeared  later 
on  in  the  Kantian  distinction  between  the  forms  of  per- 
ception and  the  matter  of  sensation.  This  distinction  was 

1 Cf.  a passage  out  of  his  lost  work  on  sensation  quoted  by  Nemesius, 
De  natura  hominis,  chap.  VI. 

2 Prime . phil.,  I,  66;  IV.R89,  197;  and  especially  Dioptr.,  IV,  6. 


THEORIES  OF  SENSATION 


275 


not  originally  used  in  a psychological  sense,  but  it  be- 
came almost  more  important  for  the  separation  of  sensa- 
tion and  perception  theories  than  Locke’s  distinction  be- 
tween primary  and  secondary  qualities.  To  be  sure,  we  do 
not  look  for  this  development  among  the  thinkers  wrho 
are  classed  as  the  direct  heirs  to  the  philosophy  of  Kant. 
It  was  rather  the  natural  science  of  the  day  that  appro- 
priated this  Kantian  distinction  and  brought  it  into  relation 
with  physiological  theories. 

(b)  The  Theory  of  Specific  Energy  of  the  Nerves 

In  the  theories  of  sensation  there  dominated  for  a long 
time  the  original  objective  opinion  that  the  qualities  of 
sensation  were  qualities  of  the  outer  stimuli.  It  is  custom- 
ary to  regard  the  theory  of  the  specific  energy  of  the  nerves 
as  a decisive  turning-point.  In  the  ancient  theories  of 
sensation  all  characteristics  of  the  object  were  permitted 
to  be  carried  over  into  the  perceiving  subject.  Since  the 
time  of  Descartes  the  similarity  between  sensation  and  ob- 
ject had  been  dropped,  but  the  stimulus  and  the  sensation 
remained  unquestionably  connected.  This  relation  was  even- 
tually obscured  by  the  theory  of  specific  energy;  the  sen- 
sation effect  of  a given  stimulation  now  became  dependent 
upon  the  kind  of  nerve-fibres  stimulated.  With  this  the 
ultimate  step  away  from  the  naive  objectification  of  sense- 
impressions  has  been  taken. 

It  happened  that  the  doctrine  of  the  specific  energy  of 
the  nerves  was  anticipated  from  purely  psychological  con- 
siderations. Within  the  circle  of  the  so-called  “fibre  psy- 
chologists,” the  theories  of  Bonnet1  are  an  interesting  ex- 
ample of  the  fact  that  important  insights  may  occasionally 
result  from  presuppositions  which  may  later  prove  unten- 

1 See  p.  94. 


276 


HISTORY  OF  PSYCHOLOGY 


able,  such  as  the  hypothesis,  in  this  case,  of  the  oscillations 
of  cerebral  fibres,  if  they  are  only  properly  followed  out. 
For  the  rise  of  an  idea  Bonnet  demanded  a nervous  stimu- 
lation similar  to  the  one  that  the  corresponding  sensation 
would  cause.  Now,  since  the  mind  can  call  into  existence 
several  separate  ideas  at  the  same  time,  it  must  be  possible 
to  stimulate  at  the  same  time  several  dispositions  without 
their  fusing  together.  Now  this  is  possible  only  if  each  sen- 
sation depends  upon  the  oscillation  of  a single  fibre  that 
belongs  entirely  to  that  sensation.  In  the  anatomical  struc- 
ture of  the  organ  of  hearing  Bonnet  thought  he  saw  the 
verification  of  this  hypothesis.  The  auditory  nerve  branches 
out  in  the  interior  of  the  labyrinth  and  the  cochlea,  and 
each  branch  is  sensitive  to  a particular  tone,  like  the  strings 
of  a stringed  instrument.  In  order  to  carry  out  this  hy- 
pothesis in  regard  to  vision,  Bonnet  presupposed  bundles 
of  fibres,  each  consisting  of  seven  fibres  corresponding  to 
the  principal  colors,  a simultaneous  stimulation  of  which 
would  cause  white. 

The  fame  of  the  theory  of  specific  energy  is  due,  however, 
to  the  great  physiologist  Johann  Muller,  who  first  came 
upon  the  idea  in  the  field  of  visual  sensation1  and  later 
on  formulated  the  fundamental  fact  in  a general  manner: 
“Sensation  is  not  the  conduction  of  a quality  or  a state  of 
an  external  body  to  consciousness,  but  it  is  the  conduction 
of  the  quality  or  the  state  of  a sensory  nerve  to  conscious- 
ness, occasioned  by  some  external  cause,  and  these  qual- 
ities differ  in  the  different  sensory  nerves,  i.  e.,  the  nerves 
possess  specific  energy.”2  This  idea  that  the  difference  of 
sense  qualities  depended  upon  the  characteristics  of  the 
sensory  nerves  was  a clear  and  complete  expression  of 
physiological  knowledge  at  the  time  when  the  structure 

1 Zur  vergl.  Physiol,  des  Gesichtssinns,  etc.,  1826. 

2 Handb.  d.  Physiol,  d.  Mensch.,  II,  1840. 


THEORIES  OF  SENSATION 


277 


of  the  separate  sense-organs  was  known  only  in  its  broad 
outline. 

Helmholtz  followed  on  with  the  logical  consequences  of 
this  principle  and  extended  its  validity  to  apply  to  the 
sensation  differences  within  a specific  field  of  sensation. 
The  combination  of  Young’s  hypothesis  of  three  nervous 
processes  corresponding  to  the  different  principal  colors 
along  with  the  theory  of  the  specific  energy  of  the  nerves 
led  Helmholtz  to  the  presupposition  of  three  specifically 
different  visual  substances1  to  which  there  correspond  in 
the  brain  just  as  many  systems  of  nerve-cells.  The  rock 
upon  which  the  Helmholtz  theory  foundered  was  the  fact, 
discovered  later,  that  the  nerves  are  relatively  indifferent 
conductors  of  stimuli  set  up  in  them.  This  forced  thinkers 
back  to  the  much  less  probable  hypothesis  that  the  specific 
sensation  process  takes  place  in  the  central  organ. 

Against  the  great  authority  which  the  principle  of  spe- 
cific energy  enjoyed  among  the  majority  of  physiologists 
evolutionary  considerations  could  only  make  slow  headway. 
In  the  time  of  Muller  the  permanency  of  species  was  still 
maintained  in  the  natural  sciences,  and  the  theory  of  ori- 
ginally different  sensation  elements  was  something  that 
seemed  to  support  this  belief.  Since  the  time  of  Darwin, 
however,  several  investigators,  such  as  G.  H.  Lewes  (1860) 
and  A.  Horwicz  (1872),  drew  the  logical  consequences  of 
the  principle  of  evolution  for  the  theories  of  sensation. 
Characteristic  for  the  belief  in  the  integrity  of  the  separate 
senses  is  the  peculiar  interpretation  of  such  physiological 
discoveries  as  could  have  thrown  light  precisely  upon  this 
point  of  the  genetic  connection  of  the  senses.  When  Goltz,2 
for  example,  discovered  that  the  semicircular  canals  took 
no  part  in  acoustical  stimulations  but  that  they  were  an 
organ  contributing  sensations  of  equilibrium  and  of  the 
1 Cf.  below,  pp.  290  f.  2 Pfliig.  Arch.,  Bd.  Ill,  1870. 


278 


HISTORY  OF  PSYCHOLOGY 


movements  of  the  body,  it  was  looked  upon  as  a sixth  sense 
and  placed  alongside  of  the  others.  The  similarity  of  these 
sensations  to  pressure  sensations  remained  unnoticed,  as  well 
as  its  close  connection  with  the  organ  of  hearing  from  the 
point  of  view  of  evolution. 

A successful  attack  against  the  theory  of  the  specific 
energy  of  the  nerves  was  made  by  J.  Ranke  in  the  intro- 
duction of  his  concept  of  “transition  organs,”  which  in  the 
lower  animals  take  care  of  all  kinds  of  perceptions  that  in 
higher  stages  of  evolution  are  assigned  to  different  organs.1 
The  hearing  rods  of  many  insects  and  the  touch  rods 
represent  a slightly  differentiated  form  of  an  organ  of 
touch.  In  a similar  manner  he  ascribed  to  the  so-called 
organ  of  vision  of  the  leech  the  functions  both  of  touch  and 
of  taste.  But,  however  forcibly  the  facts  of  comparative 
anatomy  and  physiology  might  demand  a great  limitation 
of  the  principle  of  the  specific  energy  of  the  nerves,  a great 
many  physiologists  still  consider  it  of  much  importance.  In 
the  most  recent  times  W.  Nagel2  tried  to  set  up  alongside 
of  this  principle  the  principle  of  the  specific  disposition  of 
the  sense-organs.  Each  sense-organ  is  specially  disposed  for 
a particular  kind  of  stimulus  through  a specifically  different 
sensitivity  and  receptivity,  whereas  for  other  stimuli  it  is 
absolutely  or  relatively  insensitive. 

The  extraordinary  importance  that  the  principle  of  the 
specific  energy  of  the  nerves  seemed  originally  to  gain  for 
psychology  was  obviously  a consequence  of  the  philosophi- 
cal presuppositions  suggested  above.  Since  that  time  the 
more  it  became  a physiological  principle,  the  more  the  psy- 
chological interest  turned  toward  theories  of  the  special  kinds 
of  sensations. 

1 Zeitschr.  f.  wissensch.  Zoologie,  Bd.  XXV,  1875. 

2 Bibliotheca  Zoologica,  Leuckart  and  Chun,  Bd.  XVIII,  1894. 


THEORIES  OF  SENSATION 


279 


2.  Theories  of  Vision 

Theories  of  vision  take  a prominent  place  among  theories 
of  sensation  not  only  because  it  has  been  most  common  to 
deduce  general  theories  of  sensation  out  of  the  peculiarities 
of  the  sense  of  vision  but  also  because  vision  was  the  first 
to  be  theoretically  thought  out.  The  ancient  theories  of 
light  belong  to  the  field  of  natural  philosophy.  From  these 
sprang  the  problem  of  color  vision  as  a physical  problem, 
and  in  this  form  it  remained  dominant  to  the  eighteenth 
century.  It  was  only  the  distinction  between  physiolog- 
ical and  physical  optics  that  led  to  the  more  modern  theo- 
ries of  color. 


(a)  Ancient  Theories  of  Light 

The  pre-Aristotelian  theories  of  vision  fall  into  two  chief 
groups — the  one  making  use  of  visual  rays  and  the  other  of 
pictures.1  In  the  former,  objects  became  visible  to  the  eye 
by  means  of  the  rays  of  light  streaming  out  of  the  eye.  In 
this  form  it  is  related  to  the  ancient  opinion  that  the  eye 
is  fiery — an  opinion  that  was  assented  to  by  the  Hindu  phy- 
sician, Su9ruta,  who  believed  that  an  eternal  fire  burned 
in  the  lens  of  the  eye.  Later  on,  due  to  the  influence  of 
Euclid,  this  theory  became  dominant  among  the  geometer- 
opticians.  The  same  theory  appears  again  in  the  Katoptrics 
of  Heros,  and  Cleomedes  and  Ptolemy  accepted  it.  All  the 
scientific  optics  of  antiquity  was  founded  upon  this  theory. 

The  Stoic  theory  of  air  tension  is  merely  a modification 
of  the  visual-ray  theory.  According  to  this  theory  the 
visual  pneuma  or  air,  coming  down  from  the  central  organ 
into  the  pupil,  gathers  together  the  air  between  the  eye 
and  the  object  into  a cone,  the  point  of  which  lies  in  the  eye, 
1 Cf.  A.  E.  Haas,  Arch.  f.  Gesch.  d.  Philos.,  Bd.  XX,  1907,  p.  345. 


280 


HISTORY  OF  PSYCHOLOGY 


and  the  base  coincides  with  the  visible  object.  With  this 
cone  the  eye,  as  it  were,  feels  the  objects  and  receives  an  im- 
pression of  their  form.  We  are  able  to  see  more  easily  by 
day  than  by  night  simply  because  the  air  is  rarefied  by  light 
and  can  be  more  easily  gathered  together. 

Very  soon,  however,  the  picture  theory  arose  in  opposi- 
tion to  the  visual-ray  theory.  In  this  the  movement  giving 
rise  to  the  impression  was  supposed  to  take  place  in  exactly 
the  opposite  direction,  from  the  object  into  the  eye.  In 
the  original  formulation  of  this  theory  by  Democritus  the 
pictures  themselves  do  not  penetrate  into  the  eye,  but  only 
a copy  of  them  produced  in  the  air,  and  the  clearness  of 
this  copy  decreases  with  increasing  distance.  We  should 
be  able  to  see  an  ant  crawling  on  the  dome  of  the  sky  if  it 
were  not  that  the  intervening  space  is  filled  with  air.  What 
strikes  us  in  such  an  explanation  is  the  absolute  disregard 
to  the  dioptric  changes  of  the  perceptual  picture.  In  a 
similarly  naive  fashion  our  perception  of  distance  is  ex- 
plained by  the  fact  that  the  pupil  comes  into  contact  with 
the  shaft  of  air  forced  upon  it  by  the  pictures.  Later  on 
Epicurus  simplified  this  view  by  supposing  that  copies  of 
all  objects  are  continually  being  given  off  from  their  sur- 
faces in  the  form  of  thin,  film-like  substances  which  pass 
through  the  air  into  the  eye. 

Aristotle  was  the  first  to  recognize  that  the  process  of 
vision  presupposed  an  impression  of  the  object  upon  the  eye, 
which  was  produced  by  the  partly  actually  and  partly  po- 
tentially diaphanous  intervening  medium.  It  is  also  with 
him  that  the  first  theory  of  color  originates.  It  goes  beyond 
the  beginnings  made  by  Empedocles  with  his  four  principal 
colors,  white,  black,  red,  and  yellow,  set  up  as  parallel  to 
the  four  elements.1  Aristotle  deduced  color  sensations  from 
the  diaphanous  medium  existing  between  the  organ  of  vi- 
1 Theophrastus,  de  sens.,  59. 


THEORIES  OF  SENSATION 


281 


sion  and  the  object  and  presupposed  that  some  numerical 
relation  lay  at  the  basis  of  the  differences  in  color  just  as  in 
the  case  of  tones.1  The  treatise  On  Color,  belonging  to  the 
Aristotelian  school,  treats  of  the  origin  of  colors  out  of  a 
mixture  of  black  and  white  as  a purely  physical  problem. 
Many  of  the  facts  of  color-mixture  must  have  been  known 
at  this  time.  According  to  Pliny  the  old  Greek  painters 
knew  how  to  produce  all  the  colors  out  of  four  color  sub- 
stances. One  of  the  old  paintings  chemically  analyzed  by 
Davy  showed  only  a small  number  of  different  color  sub- 
stances. 

During  the  closing  centuries  of  the  ancient  period  there 
arose  again  the  idea  that  the  soul  had  a power  of  working  at 
a distance  without  any  medium — an  opinion  that  Heraclitus 
had  formerly  held  when  he  maintained  that  the  soul  par- 
ticipated in  vision  and  considered  sensation  itself  as  a kind 
of  volition.  In  such  a way  Plotinus  explained  vision  as  a 
mystical  sympathy  between  the  soul  and  its  object,  which 
was  at  most  disturbed  by  the  medium  existing  between  the 
eye  and  its  object.  The  seeming  diminution  of  distant 
objects  he  explained  as  due  to  their  indistinct  color.  And 
in  this  he  reminds  us  of  Aristotle  who  also  tried  to  explain 
the  perception  of  certain  spatial  relations  by  means  of  color. 
Later  on  in  the  Patristic  period  Lactantius  and  Augustine 
compared  the  eyes  with  windows  through  which  the  soul 
views  the  objects  of  the  outer  world.  This  shows  that  any1 
real  appreciation  of  the  problem  underlying  sensation  has 
been  absolutely  lost. 

Alexander  of  Aphrodisias  (about  200  A.  D.),  in  his  inter- 
esting discussion  of  ancient  theories  of  light,  takes  issue 
with  the  pre-Aristotelian  theory  of  the  visual  ray  and  de- 
nies that  the  rays  of  light  can  be  material.2  The  trans- 

1 De  sensu  et  sensibili,  cap.  3. 

2 Cf.  J.  Zahlfleisch,  Arch.  f.  Gesch.  d.  Phil.,  Bd.  VIII,  1895,  p.  373. 


282 


HISTORY  OF  PSYCHOLOGY 


formation  of  this  theory  by  the  Stoics,  who  compared  visual 
perception  to  the  touching  of  uneven  surfaces  on  the  ground 
with  the  help  of  a stick,  was  held  by  Alexander  to  be  un- 
tenable because  of  the  various  distances  of  the  objects. 
Similar  objections  underlie  the  theory  that  the  form  of  con- 
tours is  taken  on  by  the  air  and  then  transplanted  into  the 
eye.  Further,  a visual  impression  is  obtained  only  of  the 
side  of  the  object  turned  toward  the  eye.  It  is,  therefore, 
impossible  to  see  the  whole  object.  Although  Alexander 
rightly  criticises  the  theory  he  is  opposing  for  confusing 
sensation  and  judgment,  yet  his  own  conception  of  vision 
remains  a very  primitive  one. 

In  regard  to  the  other  conception,  that  pictures  of  the 
objects  affect  the  eye,  it  is  argued  that  the  continual  giving 
off  of  pictures  would  impair  the  objects  themselves.  Nei- 
ther could  the  distance  be  judged  nor  the  geometrical  form 
be  recognized,  since  in  spite  of  eye  movements  it  remains 
inexplicable  how  a unified  image  could  arise  out  of  separate 
impressions.  If,  lastly,  we  presuppose  that  emanations 
from  the  object  find  their  way  to  the  eye,  we  would  not 
be  able  to  see  near  and  distant  objects  simultaneously. 

The  ancients  seem  never  to  have  risen  much  above 
this  kind  of  criticism.  Purely  psychological  considerations 
failed  in  face  of  that  peculiar  objectivism  that  sought  in 
fantastic  fashion  to  invent  objective  substrata  for  the  sen- 
sations as  well  as  for  the  ideational  images  of  the  sense  of 
sight.  Of  all  the  ancient  theories  of  light,  that  one  lasted 
longest  that  made  the  greatest  concessions  to  this  objec- 
tivism, namely  the  picture  theory.  By  Scholasticism  this 
theory  was  transformed  to  the  extent  that  only  the  form 
of  objects  penetrated  into  the  sense-organ.  Buridan  called 
light,  as  content  of  sensation  (lumen),  a species  of  objective 
light  (lux). 

In  the  philosophy  of  nature  of  the  Renaissance  we  again 


THEORIES  OF  SENSATION 


283 


meet  with  the  ancient  theory  of  colors,  a knowledge  of 
which  is  principally  due  to  the  translation  by  Simon  For- 
tius (1537)  of  the  treatise  On  Color  belonging  to  the  Peri- 
patetic school.  Telesius1  also  was  influenced  by  ancient 
thought  when  he  tried  to  deduce  all  the  colors  from  the 
principle  of  warmth  and  cold.  But  for  the  most  part  the 
traditional  theories  of  color  were  swamped  by  the  occult 
sciences,  which  were  filled  with  enthusiastic  wonder  at  the 
colors  and  their  effects.  This  is  the  time  when  Paracelsus 
advised  those  afflicted  with  melancholia  to  wear  chains  of 
coral  because  of  the  stimulating  effect  of  the  red  color,  and 
when  Scaliger  confessed  in  regard  to  colors  that  they  are 
buried  in  the  darkest  depths  of  human  ignorance.  Whatever 
scientific  thought  was  achieved  during  this  period  was,  in 
regard  to  color,  restricted  to  the  physical  aspect  of  the  prob- 
lem. 


( b ) Separation  of  Physical  and  Physiological  Optics 

The  distinction  between  the  physical  and  the  physio- 
logical problems,  which  wrere  fused  together  in  the  old 
theories,  was  prepared  for  by  Kepler.  He  was  the  first  to 
lay  the  basis  for  a physiological  optics,  inasmuch  as  he 
called  attention  to  a number  of  peculiarities  in  visual  sen- 
sation, such  as  irradiation  and  the  colored  fluctuation  of 
after-images.  But  in  his  fantastic  description  of  the  colors 
he  nevertheless  proved  himself  a child  of  his  age.  In  the 
same  way  empirical  and  fantastic  ideas  are  mingled  in  the 
Optics  (1613)  of  the  Jesuit  Franciscus  Aguillonius.  The 
quincunx  of  colors,  white,  yellow,  red,  blue,  black,  he  di- 
vided according  to  the  manner  of  their  appearance  into  true, 
apparent,  and  intentional  colors,  and  of  these  the  apparent 
ones,  such  as  those  of  the  rainbow,  he  declared  as  inexpli- 
cable, and  even  as  a divine  secret. 

1 De  colorum  generatione,  1570. 


284 


HISTORY  OF  PSYCHOLOGY 


In  his  historical  review  of  the  best-known  theories  of 
color,  Robert  Boyle1  deals  first  of  all  with  the  Aristotelian 
and  Platonic  theories,  in  which  color  is  taken  to  be  a kind  of 
flame  made  up  of  very  minute  particles,  which  are  cast  by 
the  object  into  the  eye,  and  the  shape  of  which  corresponds 
to  the  pores  of  the  eye.  Then  he  goes  on  to  deal  with  some 
atomic  theories  which  explain  color  as  a mixture  of  light 
and  darkness.  The  chemists  derive  it  from  sulphur  or 
from  salt  or  from  mercury.  And,  lastly,  the  Cartesians 
explain  color  as  resulting  from  the  different  kinds  of  move- 
ment made  by  the  atoms  that  form  light.  Boyle  would 
seem  to  tend  toward  this  last  hypothesis  although  in  a very 
cautious,  hesitating  manner.  The  rays  of  light  modified 
by  reflecting  or  refracting  bodies  produce  that  sensation 
which  we  are  accustomed  to  call  color.2  Nicholas  Male- 
branche3  revives  an  analogy  between  light  and  sound  proc- 
esses that  had  been  previously  hinted  at  by  Aristotle. 
Analogous  to  air  vibrations  in  the  process  of  audition,  he 
assumed  periodical  oscillations  in  the  smallest  particles  of 
the  illuminating  body,  and  these  oscillations  were  carried 
over  to  the  eye  by  means  of  a very  delicate  kind  of  matter, 
which  in  its  turn  affected  the  eye  by  pressure. 

Far  more  important  than  such  speculative  theories  of 
color  were  the  researches  of  Newton,  which  led  to  a definite 
separation  between  physiological  and  physical  optics.  By 
means  of  his  proofs  of  the  composition  of  white  light,  New- 
ton liberated  the  thinking  of  physicists  from  the  Aristote- 
lian theory  of  color.  The  most  important  fact  which  this 
helped  to  establish  was  the  arrangement  of  light  sensations 
according  to  the  common  characteristic  of  brightness  in  a 

1 Experiment a et  considerationes  de  coloribus,  seu  initium  historice 
experimentalis  de  coloribus  a Roberto  Boyle,  1665. 

2 Cf.  Goethe,  Geschichte  der  Farbenlehre. 

3 Reflexions  sur  la  lumiere  et  les  couleurs  et  la  generation  du  feu  par  le 
Pbre  Malebranche,  1669. 


THEORIES  OF  SENSATION 


285 


continuous  series  from  black  to  white.  This  phenomenon, 
which  forces  itself  upon  subjective  observation,  had  arrested 
the  attention  of  the  intuitive  thinkers  of  all  times;  it  was 
only  later  that  it  found  its  classical  expression  in  Goethe’s 
theory  of  color.  Newton  himself  never  departed  from  the 
field  of  physical  analysis,  in  which  he  was  a master;  he 
never  interested  himself  in  the  physiological  problems.  His 
physical  explanation  of  the  sensation  black  was  that  it  was 
a mixture  of  all  colors,  like  white,  and  only  differed  from 
white  because  of  the  absence  of  light.1  This  made  black  a 
physical  characteristic  of  light,  whereas  in  reality  the 
objective  correlate  of  the  sensation  is  found  in  the  physio- 
logical condition  of  the  retina  when  not  stimulated.  New- 
ton really  never  freed  himself  from  the  objectivism  of  the 
physicists.  His  famous  statement  that  light  could  be 
divided  into  seven  separate  colors  really  interchanged  sub- 
jective and  objective.  In  the  same  way  the  analogies 
between  tones  and  colors,  which  date  from  this  time,  also 
proved  deceptive.  Newton  drew  up  a relationship  be- 
tween the  breadth  of  the  spectral  bands  and  the  string 
lengths  corresponding  to  the  tones  of  the  Phrygian  scale, 
and  this  Father  Castel  took  as  a basis  for  the  construction 
of  his  color  piano.  However,  with  the  knowledge  of  the 
varying  dispersing  power  of  refracting  media,  Newton’s 
relationship  was  shown  to  be  nothing  but  an  accidental 
analogy  dependent  upon  the  technical  conditions  of  pro- 
ducing his  colors. 

The  old  Aristotelian  idea  that  colors  are  mixtures  of 
light  and  shade  did  not  entirely  disappear  in  spite  of  all 
the  advances  made  in  physical  optics.  About  the  end  of 
the  seventeenth  century,  Lazarus  Nuguet2  took  up  this 
view  and  also  sought  to  make  a fourfold  classification  of 

1 Lectiones  opticce,  Opera,  t.  II,  p.  225. 

2 Journal  de  Trevoux,  April,  1705,  p.  675. 


286 


HISTORY  OF  PSYCHOLOGY 


all  the  phenomena  included  under  the  name  of  color,  i.  e., 
colors  existing  (1)  in  colored  lights,  (2)  in  transparent 
media,  (3)  in  the  organ  of  sight,  and  (4)  in  the  soul.  In 
this  classification  we  must  recognize  the  attempt  to  discrimi- 
nate between  the  physical,  physiological,  and  psychological 
conceptions  of  color,  which  he  clearly  distinguishes,  ac- 
cording to  the  point  of  view  adopted.  This  does  not  apply 
to  his  discussion  of  the  action  of  colors  in  transparent  media, 
which  is  reminiscent  of  Aristotle. 

The  most  famous  resuscitation  of  the  Aristotelian  theory  of 
color  is  met  with  in  Goethe’s  theory,1  which  has  as  its  prin- 
cipal thought  the  notion  that  light  and  dark  must  be  mixed 
together  in  order  to  produce  color.  Goethe  thought  he 
found  in  opaque  media  the  kind  of  darkening  necessary 
for  the  production  not  of  gray  but  of  colors.  These  at- 
tempts at  a physical  theory  stand  in  contrast  to  Newton’s 
theory  in  much  the  same  way  as  his  artistic  thinking  based 
on  living,  concrete  imagery  stands  in  contrast  to  the  analytic 
thinking  of  the  scientist.  Newton’s  investigations  had  pre- 
pared the  way  for  a physiology  of  light  sensations  and  an 
empirical  knowledge  of  their  subjective  conditions.  Goethe 
was  the  one  who  had  described  so  brilliantly  the  sense 
value  and  the  ethical  effect  of  colors,  and  so  it  was  cer- 
tainly the  right  feeling  that  made  him  oppose  a theory  that 
threatened  to  destroy  the  beautiful  sense  appearance  of 
sensations. 

Schopenhauer  tried  to  approach  the  problem  of  color 
vision  as  a physiological  problem  from  the  standpoint  of 
Goethe’s  theory  of  color.  He  explained  color  with  the  help 
of  a concept  borrowed  from  contemporary  natural  philoso- 
phy, i.  e.,  the  concept  of  polarity  for  the  qualitatively 
different  activities  of  the  retina.  His  polemic  against  the 
undulation  theory  during  the  fifties  of  the  nineteenth  cen- 
1 Beitrdge  zur  Optik,  1791,  1792.  Zur  Farbenlehre,  1810. 


THEORIES  OF  SENSATION 


287 


tury  stands  out  in  the  history  of  optics  like  an  erratic  boulder 
which  has  survived  from  ages  long  since  past. 


(c)  Modern  Color  Theories 

However  varied  the  lines  of  thought  in  the  newer  theories 
of  color  may  be,  they  nevertheless  differ  from  the  previously 
discussed  theories  by  this  common  characteristic,  i.  e.,  of 
paying  attention  to  the  subjective  conditions  as  well  as  to 
the  temporal  and  spatial  relations  of  light  sensations.  They 
likewise  all  agree  in  a retreat  from  that  original  objectivism 
which  had  supposed  color  sensations,  like  most  other  sensa- 
tions, to  be  characteristics  of  outer  objects.  Observations 
about  the  temporal  and  spatial  relations  of  light  sensation 
reach  back  to  a much  earlier  period  than  any  theoretical  use 
of  them  which  goes  beyond  primitive  attempts  at  explana- 
tion.1 

In  the  seventeenth  century  the  after-images  of  windows 
were  described  in  their  main  outlines  not  as  a scientific  fact 
but  as  a clever  conjuring  feat.  We  are  told  that  Bona- 
cursius  proved  to  the  Jesuit  Athanasius  Kircher  that  one 
could  see  in  the  dark  no  less  than  in  the  light.2  Follow- 
ing the  instructions  of  Bonacursius,  Kircher  fixated  stead- 
ily a drawing  that  had  been  put  in  the  window  opening 
of  an  otherwise  totally  dark  room  and  then  after  the  room 
had  been  darkened  saw  it  actually  reappear  on  a clean  sheet 
of  white  paper.  Kircher’s  explanation  that  the  eye  gives 
out  again  light  that  it  has  absorbed  reminds  us  distinctly 
of  ancient  theories  of  sensation.  The  opinion  closely  re- 
lated to  this,  viz.,  that  objective  light  is  actually  developed 
in  the  eye,  as  proved  by  the  light  caused  by  mechanical 
pressure  on  the  eye,  has  continued  dowm  to  modern  times. 

1 Cf.  Helmholtz,  Physiol.  Optik,  2 Aufl.,  p.  536. 

2 A.  Kircher,  Ars  magna,  1646,  p.  162. 


288 


HISTORY  OF  PSYCHOLOGY 


Appeal  was  made  to  the  cases  of  men  who  were  said  to 
be  able  to  see  in  the  dark,  like  Tiberius  Caesar,  Cardanus, 
Kaspar  Hauser.  Newton  considered  after-images  as  purely 
psychical  phenomena,  since  one  could  recall  them  some  time 
after  their  disappearance  by  means  of  a special  direction 
of  the  attention,  as  in  the  case  of  the  sun. 

To  arrive  at  a physiological  theory  of  these  phenomena, 
Jurin1  presupposed  a continuance  of  the  stimulus  and  partly 
the  appearance  of  the  opposite  excitation  due  to  the  cessa- 
tion of  a strong  sensation.  The  opposite  opinion  to  this, 
i.  e.,  that  after-images  arise  because  of  a decreased  sensi- 
bility of  the  fatigued  retina,  was  later  opposed  by  Father 
Scherffer,2  who  based  his  arguments  chiefly  upon  the  ma- 
terial gathered  by  the  naturalist  Buffon.  Prieur  de  la 
Cote-d’Or3  set  up  the  relationship,  so  often  used  later 
on,  between  after-images  and  the  phenomena  of  contrast. 
This  was  again  modified  by  Brewster,4  who  showed  that 
there  is  developed  with  each  color  a complementary  color 
tending  to  dull  the  original  color. 

Theories  of  this  kind  were  brought  to  a provisional  ter- 
mination by  the  investigations  of  Plateau5  and  Fechner.6 
The  former  gave  consistent  expression  to  the  theories  that 
presuppose  contrasting  activities  in  the  retina;  the  latter 
explained  negative  after-images  by  the  principle  of  fatigue. 
According  to  the  judgment  of  Helmholtz  these  two  inves- 
tigations indicated  the  status  of  science  during  the  fifth 
decade  of  the  nineteenth  century — a decade  that  was  so 
important  for  optical  research. 

1 Jurin,  “Essay  on  Distinct  and  Indistinct  Vision,”  p.  170  in  Smith’s 
Optics. 

2 Scherffer,  Abhandlung  von  den  zufalligen  Farben,  1765. 

3 Ann.  de  Chim.,  Bd.  LIV,  1804,  p.  1. 

4 Phil.  Mag.,  1833,  II,  p.  89;  IV,  p.  354. 

5 Essai  d’une  Theorie  generate  comprenant  V Ensemble  des  apparences 
visuelles  qui  succedent  a la  contemplation  des  objets  colores,  Bruxelles,  1834. 

6 Pogg.  Ann.,  1838,  Bd.  XLIV,  pp.  221,  513;  Bd.  XLV,  p.  227. 


THEORIES  OF  SENSATION 


289 


In  the  field  of  color  contrast  Leonardo  da  Vinci1  was  one 
of  the  first  to  point  out  that  colors  of  equal  perfection  pro- 
duced the  most  beautiful  effect  when  placed  next  to  their 
opposites,  e.  g.,  white  with  black,  red  with  green,  yellow  with 
blue.  The  coloring  of  shadows  in  the  light  of  the  rising 
and  setting  sun  was  considered  objective  because  shadows 
caused  by  the  light  of  the  blue  sky  are  really  blue.  It  was 
left  for  Rumford2  to  prove  the  subjective  nature  of  the  col- 
oring by  observing  the  shadows  through  a tube  and  thereby 
noting  how  the  colors  disappeared.  After  this  Plateau3 
incorporated  the  phenomena  of  contrast  in  his  theory  of 
after-images.  Not  only  in  time  are  opposing  states  of  the 
retina  arranged  alongside  of  each  other,  but  also  in  regard 
to  the  spatial  extent  of  the  excitation,  in  such  a manner 
that  around  the  stimulated  area  there  is  first  of  all  a zone 
of  a certain  nature  which  is  shown  in  the  phenomena  of 
irradiation,  and  then  adjacent  to  it  but  farther  away  is  the 
opposite  zone  which  produces  the  contrast. 

Our  knowledge  of  the  temporal  relations  of  light  sensa- 
tion received  its  most  important  addition  in  the  discovery 
of  the  differences  between  daylight  and  twilight  vision  and 
our  knowledge  of  the  spatial  relations  in  the  discovery  of 
the  differences  between  peripheral  and  central  vision.  And 
with  this  we  have  arrived  at  the  standpoint  of  the  most 
modern  theories  of  color.  The  differences  between  them 
would  seem  to  be  due  in  great  part  to  their  various  points 
of  departure,  i.  e.,  in  the  group  of  facts  in  physiological 
optics  which  is  regarded  as  fundamental.  The  hypotheses 
that  start  with  the  facts  of  color-mixture,  i.  e.,  the  objec- 
tive conditions  of  visual  sensation,  can  be  grouped  together 
as  the  three-color  theories;  opposed  to  this  we  have  the 

1 Leonardo  da  Vinci,  Trattato  della  pittura,  1651,  cap.  CC. 

2 Philos.  Transact.,  LXXXIV,  p.  107. 

3 Ann.  de  Chim.  et  de  Phys.,  1834,  LVIII,  p.  339. 


290 


HISTORY  OF  PSYCHOLOGY 


four-color  theory,  which  starts  with  the  subjective  arrange- 
ment of  visual  sensations.  Out  of  the  critical  discussions  of 
these  theories  there  have  grown  the  opinions  that  reflect 
the  present  status  of  these  theoretical  problems. 

(1)  THE  THREE-COLOR  THEORY 

The  deduction  from  the  laws  of  color-mixture  that  three 
sensation  processes  independent  of  one  another  are  called 
into  being  by  the  external  stimulus  was  first  of  all  made 
by  Thomas  Young.1  The  basic  outline  of  his  theory  was 
determined  by  the  fact  that  he  ascribed  to  the  sensory 
nerves  only  those  characteristics  that  had  been  discovered 
for  the  motor  nerves  of  man  and  the  animals,  i.  e.,  the 
change  between  rest  and  activity.  The  former  corresponds 
to  the  sensation  of  black  and  the  latter  to  that  of  white 
or  colored  light.  The  simple  color  sensations,  from  the 
mixture  of  which  all  others  arise,  must  be  arranged  at  the 
three  corners  of  the  color-triangle.  Corresponding  to  this, 
Young  presupposed  three  kinds  of  nerve-fibres  in  the  eye, 
which,  if  stimulated  separately,  would  give  the  sensations 
of  red,  green,  and  violet  respectively.  Homogeneous  light 
excites  these  three  species  of  fibres  in  varied  degree  accord- 
ing to  the  length  of  its  waves.  Of  course,  the  facts  of  color- 
mixture  forming  the  basis  of  Young’s  theory  had  long  been 
known.  Before  Newton’s  time  the  trinity  of  principal 
colors,  red,  yellow,  and  blue,  had  been  mentioned  by  Waller 
as  a scientifically  acknowledged  fact,  in  an  attempt  at  a 
classification  of  the  colors.  The  new  part  of  Young’s  theory 
was  the  hypothesis  of  the  three  physiological  processes. 

This  most  important  part  of  the  theory  was  introduced 
into  modern  optics  by  Helmholtz.  The  application  of  the 
principle  of  specific  sensations  to  the  separate  nerve-fibres 
1 Th.  Young,  Lectures  on  Natural  Philosophy , 1807. 


THEORIES  OF  SENSATION 


291 


led  him  to  the  hypothesis  of  special  fibres  for  red,  green, 
and  violet  sensations.1  The  effect  of  different  kinds  of 
light  upon  these  elements  singly  could  remain  undetermined 
if  only  each  species  of  fibres  was  dependent  in  a different 
manner  upon  the  wave-length.  If  the  relation  between  the 
physiological  effect  and  the  wave-length  were  represented 
by  a curve,  then  the  curves  for  the  red,  green,  and  violet 
components  would  have  to  differ  in  a characteristic  manner. 

In  Helmholtz’s  theory  of  color,  which  later  became  so 
famous,  we  can  separate  the  principal  thought,  i.  e.,  that 
changes  in  the  state  of  the  organ  of  vision  are  possible  in 
three  directions,  from  the  physiological  interpretation, 
which  presupposes  in  the  nerve  substance  only  single 
changes,  i.  e.,  changes  that  deviate  from  the  state  of  repose 
in  one  single  direction.2  These  special  hypotheses  as  to 
the  immediate  effect  of  light  were  later  dropped,  and  the 
expression  “component”  was  introduced  for  the  different 
parts  of  the  color-sensation  process.  With  this  Helmholtz’s 
theory  became  a three-component  theory,  and  it  is  in  this 
form  that  it  is  still  under  discussion  at  the  present  day. 

We  must  also  bear  in  mind  that  at  that  time  the  concept 
of  an  elementary  sensation  was  not  recognized  in  the 
sense  in  which  it  is  used  in  modern  psychology.  If  at 
the  present  time  an  elementary  sensation  is  defined  as  one 
which  cannot  be  further  split  up  into  parts  even  after  the 
most  careful  subjective  analysis,  then  it  would,  of  course, 
be  a contradiction  in  Helmholtz’s  color  theory  to  say  that 
red,  green,  and  violet  are  basic  sensations  and  that  white 
is  a mixed  sensation.  It  is  clear,  however,  that  this  con- 
tradiction has  crept  into  the  theory  because  of  the  subse- 
quent shift  of  meaning  of  the  concept  “basic  sensation.” 

1 Cf.  p.  277. 

2 Cf.  von  Kries,  “Die  Gesichtsempfindungen,”  in  Nagels  Handbuch 
d.  Physiol.,  Ill,  1905,  pp.  129  ff.  and  266  ff. 


292 


HISTORY  OF  PSYCHOLOGY 


Not  a psychological  but  a physiological  meaning  is  attached 
to  this  concept  by  Helmholtz.  In  spite  of  occasional  re- 
marks that  the  three  basic  sensations,  and  especially  red 
and  violet,  differ  from  the  others  in  a purely  subjective  man- 
ner due  to  the  greater  glow  of  their  color  saturation,  never- 
theless the  chief  meaning  of  the  concept  “basic  sensation” 
is  its  physiological  meaning. 

(2)  THE  FOUR-COLOR  THEORY:  OPPOSITION  AND 
DEVELOPMENT 

Red,  yellow,  green,  and  blue  have  been  recognized  as  the 
four  chief  colors  since  the  time  of  Leonardo  da  Vinci,  and  it 
was  Aubert  who  was  the  first  to  declare  them  the  principal 
sensations  in  the  physiological  sense.  The  principles  by 
means  of  which  a theory  of  color  could  be  arrived  at  were 
to  be  sought  partly  in  general  philosophical  opinions,  as, 
for  example,  in  Mach’s  axiom  that  each  psychic  entity 
corresponds  to  a physical  one.1  But  such  a conclusion 
leading  back  from  the  sensations  and  their  arrangement  to 
the  physiological  processes  could  arrive  at  a special  the- 
ory of  color  only  when  special  presuppositions  as  to  the 
nature  of  the  physiological  processes  themselves  had  been 
reached. 

In  this  way  it  was  E.  Hering2  who  gave  the  four-color 
theory  its  authoritative  form,  by  making  it  a theory  of 
contrast-colors.  By  calling  the  totality  of  color  sensations 
variegated  (bunt),  he  tried  to  avoid  the  original  double 
meaning  of  the  word  color  ( Farbe ),  which  even  in  Goethe’s 
time,  following  the  old  meaning,  was  used  to  denote  all 
qualities  of  light.  The  special  presuppositions  which  He- 
ring postulated  consist  in  supposing  that  processes  of  an 

1 Mach,  Arch.  f.  Anat.  u.  Phys.,  1865,  pp.  634/. 

2 Sitzungsber.  d.  Wien.  Akad.,  Math.-Naturw.  Kl.t  1874,  69  (3). 


THEORIES  OF  SENSATION 


293 


opposite  nature  take  place  in  the  nerves,  i.  e.,  the  decom- 
position and  recomposition  of  highly  complex  substances. 
Let  the  processes  of  the  first  group  be  called  dissimilating  or 
D processes  and  those  of  the  second  assimilating  or  A proc- 
esses, then  the  contrasting  pairs  in  the  black-white  sensa- 
tion and  in  the  principal  color  sensations  can  be  looked 
upon  as  D and  A processes  in  a special  visual  substance. 
The  organ  of  vision  is  thus  made  up  of  three  visual  sub- 
stances to  some  extent  independent  of  each  other,  i.  e., 
white-black,  red-green,  and  yellow-blue  substances. 

It  has  been  regarded  as  a special  advantage  of  this  theory 
that  it  gives  us  a concrete  picture  of  the  psychological  ar- 
rangement of  our  sensations.  But  we  must  not  forget  that 
in  two  important  points  it  is  lacking  in  this  direct  correspon- 
dence with  the  subjective  system  of  sensations.  First  of 
all,  the  neutral  sensation  between  white  and  black  stands  in 
a relationship  to  the  two  end  sensations  of  the  white-black 
series  different  from  that  in  which  the  neutral  sensation 
gray  stands  to  a pair  of  contrast  colors.  Secondly,  there 
arises  a whole  series  of  difficulties  by  making  light  stimula- 
tion dependent  upon  six  variables,  whereas  in  the  psycho- 
logical system  of  light  sensations  the  single  sensation  can 
be  fully  accounted  for  by  three  variables.1 

The  theories  of  Hering  and  Helmholtz,  differing  as  they 
do  in  many  important  points,  were  brought  into  harmony 
in  a very  unexpected  manner  by  J.  von  Kries,  in  the  sense 
that  the  relative  truth  of  each  could  be  recognized  by  the 
other.  This  union  was  brought  about  in  part  by  the  dis- 
covery that  a differentiation  of  function  in  the  retina 
corresponds  to  the  differences  of  daylight  and  twilight 
vision  dependent  upon  the  adaptation  of  the  organ  of 
vision.  This  division  of  function  among  the  end-organs  in 
the  retina  was  interpreted  by  many  investigators  in  this 
1 Cf.  J.  von  Kries,  op.  dt.,  pp.  147  /. 


294 


HISTORY  OF  PSYCHOLOGY 


way,  namely,  that  the  cones,  occurring  chiefly  in  the  centre, 
were  responsible  for  phenomena  seen  in  daylight,  whereas 
the  rods  were  supposed  to  function  chiefly  in  dark  adapta- 
tion. This  functional  division  of  the  rods  and  cones  of  the 
retina  was  first  made  by  Max  Schultze.1  The  cones  were 
assumed  to  furnish  all  kinds  of  light  sensations  but  the 
rods  only  sensations  of  brightness.  To  this  Parinaud2  added 
the  suggestion  that  this  function  of  the  rods  depended  upon 
the  visual  purple,  the  fluorescence  of  which  gave  off  the 
substratum  for  brightness  sensations.  Deficient  production 
of  visual  purple  causes  hemeralopia  and  the  composition 
of  our  organ  of  vision  out  of  rods  and  cones  causes  the 
Purkinje  phenomenon. 

Von  Kries3  also  recognized  the  rods  as  the  bearers  of  pure 
brightness  sensations.  In  regard  to  daylight  vision  he  pre- 
supposed that  the  peripheral  processes  of  the  retina  worked 
according  to  the  three-color  component  theory.  This  zone 
theory  of  von  Kries  is  supposed  to  unite  the  theories  of 
Helmholtz  and  of  Hering.  It  does  not  attempt,  however, 
to  give  a unified  principle  embracing  the  totality  of  optical 
facts  nor  yet  a detailed  conception  of  the  nerve  processes 
underlying  those  facts. 

The  principle  generally  recognized  in  these  newer  theories, 
according  to  which  the  psychological  arrangement  of  the 
sensations  forms  the  point  of  departure,  is  also  the  basis  of 
Wundt’s  gradation  theory.  Wundt  had  at  first4  accepted 
the  ideas  involved  in  Young’s  theory,  but  even  in  the 
Grundziige  der  yhysiologischen  Psychologie,  published  in 
1874,  he  commenced  his  criticism,  especially  because  of 

1 Archiv  f.  mikroskop.  Anatomie,  1866,  2,  pp.  247  ff.  Cf.  G.  E.  Miil- 
ler,  in  Zeitschr.  /.  Psych,  u.  Physiol,  d.  Sinnesorg.,  1897,  Bd.  XIV,  pp. 
161  ff. 

2 Compt.  rend.,  XCIII,  1881,  pp.  286/. 

3 Die  Lehre  von  den  Gesichtsempfindungen,  1882. 

4 Vorlesungen  iiber  die  Menschen-  und  Tierseele,  1863,  pp.  133/. 


THEORIES  OF  SENSATION 


295 


the  close  connection  of  the  theory  with  the  principle  of  the 
specific  energy  of  the  nerves,  and  he  attempted  to  get  back 
to  the  peculiarities  contained  in  the  arrangement  of  visual 
sensations  in  the  color-circle.  It  was  chiefly  through  He- 
ring’s  work  that  he  arrived  at  the  conviction  that  brightness 
and  color  stimulation  were  to  be  looked  upon  as  differ- 
ent processes.  Later  on  any  correspondence  between  the 
primary  physical  colors  and  the  fundamental  physiological 
processes  is  unhesitatingly  denied  and  in  its  place  there  is 
set  up  the  principle  that  to  each  qualitative  or  quantita- 
tive difference  in  visual  sensation  there  corresponds  a qual- 
itative or  quantitative  difference  in  the  visual  process.1 
From  this  there  arises — to  borrow  an  expression  coined  by 
von  Ivries  in  the  study  of  tones — a gradation  theory  for 
light  sensations  which  can  also  be  distinguished  from  the 
component  theories  as  a periodicity  theory.  Inasmuch  as 
this  theory  denies  a special  place  to  the  principal  colors  in 
the  psychological  color  series,  it  is  an  example  of  the  varied 
interpretation  a principle  may  lead  to,  which  at  first  sight 
would  seem  to  imply  absolute  uniformity,  i.  e.,  the  principle 
of  the  subjective  arrangement  of  the  visual  sensations. 

Of  the  later  modifications  of  the  four-color  theory  the 
Ladd  Franklin2  theory  has  risen  to  great  prominence  espe- 
cially in  the  United  States.  Of  more  interest  to  us  than 
the  hypothetical  conception  of  the  differences  in  the  chem- 
ical disintegration  in  the  rods  and  cones  is  the  change  in 
the  evaluation  of  the  principal  colors.  Yellow  and  blue 
are  the  two  colors  that  correspond  to  a division  of  the  white 
process;  red  and  green,  on  the  other  hand,  arise  out  of 
another  division  of  the  yellow  process,  since  a mixture  of 
pure  green  and  pure  red  does  not  result  in  a colorless  sen- 

1 W.  Wundt,  Philos.  Stud.,  1888,  Bd.  IV,  pp.  310  ff. 

2 Zeitschr.  f.  Psych.,  etc.,  1893,  Bd.  IV,  pp.  211  ff.  [Mind,  N.  S.,  vol. 
XI,  p.  672.  Trs.] 


296 


HISTORY  OF  PSYCHOLOGY 


sation  but  in  a yellow.  Unfortunately,  this  theory  too 
is  lacking  in  any  empirical  determination  of  the  presup- 
posed pure  colors. 

The  theory  of  G.  E.  Muller 1 represents  the  cleverest  at- 
tempt at  a further  development  of  the  four-color  theory. 
This  theory  changes  the  concept  of  antagonism  so  that  the 
sensations  are  not,  as  with  Hering,  made  to  be  absolutely 
dependent  upon  the  relation  of  the  opposite  psychophysical 
processes.  Further,  light  is  not  supposed  to  affect  directly 
the  substratum  of  sensation  but  must  first  go  through  a 
white  substance,  a red,  a yellow,  etc.  To  this  is  added  the 
idea  of  indirect  values;  the  red  material  has,  for  example, 
an  indirect  yellow  value.  By  means  of  this  co-operation 
of  the  different  kinds  of  color  material  we  can  explain  in 
a perfect  manner  the  finer  differences  in  color-blindness. 
Inasmuch  as  Muller’s  theory  divides  the  organ  of  vision 
unequally  into  different  parts  arranged  behind  each  other, 
it  can  be  classed  as  one  of  the  zone  theories.2 

From  the  discussions  of  the  last  two  decades  one  can  see 
with  some  certainty  that  the  principle  at  first  emphatically 
laid  down,  which  used  the  subjective  peculiarities  of  visual 
sensation  in  order  to  go  back  to  definite  conclusions  as  to 
the  underlying  physiological  processes,  has  not  fulfilled  the 
promises  which  it  at  first  held  out.  Rather  there  seems  to 
have  arisen  out  of  the  numerous  failures  a demand,  always 
growing  more  imperative,  to  separate  the  problems  of  the 
physiology  of  the  organ  of  vision  from  those  of  a psychology 
of  visual  sensations.3 

1 Zeitschr.  f.  Psych.,  etc.,  Bd.  X,  1896,  pp.  1,  32;  Bd.  XIV,  1897,  pp. 
1,  161. 

2 Von  Kries,  op.  cit.,  p.  276. 

3 Cf.  the  treatment  of  the  present  position  of  the  theoretical  prob- 
lems in  von  Kries,  op.  cit.,  pp.  279  JJ. 


THEORIES  OF  SENSATION 


297 


3.  Theories  of  Audition 

In  no  other  department  of  psychology  has  the  work  of 
a single  investigator  led  to  such  unification  of  theoretical 
opinions  as  Helmholtz’s  theory  of  tone  sensations  has  ac- 
complished in  the  department  of  tone  psychology.  The 
older  attempts  at  a theory  of  audition  are  nothing  more 
or  less  than  a preliminary  history  of  the  resonance  theory. 
Further  developments  of  the  resonance  theory  dominate  all 
psychological  acoustics  since  the  time  of  Helmholtz,  except 
for  a few  isolated  attempts  to  find  an  insight  into  the  origin 
of  auditory  sensations  on  other  principles.  We  must  also 
cast  a glance  at  theories  of  consonance,  which  are  them- 
selves of  much  more  ancient  origin  than  the  real  theories 
of  audition  and  were  only  connected  up  with  the  latter  in 
recent  times.  Here  again  it  was  not  the  elementary  phe- 
nomena, the  simple  tone  sensations,  that  caused  a necessity 
for  an  explanation  to  be  felt,  but  rather  the  more  striking 
phenomena,  the  combinations  of  tones. 


(a)  Preliminary  History  of  the  Resonance  Theory 

The  main  thought  of  the  resonance  theory  belongs  to  the 
eighteenth  century.  For  the  simultaneous  direct  perception 
of  difference-tones  Condillac1  thought  that  different  perceiv- 
ing parts  in  the  organ  of  hearing  were  a necessary  require- 
ment. To  prove  the  subjectivity  of  auditory  sensations, 
Lossius  pointed  to  the  sympathetic  sounding  of  a string 
when  its  tone  is  being  sung  and  suggested  that  the  process 
in  the  ear  might  be  analogous;  “but  whether  there  are  as 
many  fibres  in  the  ear  as  there  are  fundamental  tones,  or, 
further  still,  so  many  as  to  allow  of  shades  of  difference 
1 Traite  des  sensations,  I,  VIII,  § 4. 


298 


HISTORY  OF  PSYCHOLOGY 


between  these  fundamentals,  cannot  be  determined.” 1 From 
the  anatomical  examination  of  the  end-organ,  Cotugno 
arrived  at  his  comparison  between  the  cochlea  and  a lute 
attuned  to  different  tones  ranging  from  the  cupola  to  the 
base.2 

To  these  beginnings  of  a resonance  theory  there  were 
added  purely  psychological  discussions  as  to  the  possibil- 
ity of  simultaneous  sensations.  From  the  very  beginning 
the  favorite  example  was  taken  from  tone  sensations,  ever 
since  Aristotle  answered  the  question  as  to  whether  a mul- 
tiplicity of  sensations  of  the  same  sense  could  exist  at  one 
and  the  same  time  by  pointing  out  that  this  could  happen 
only  if  they  mixed  together  like  a high  and  low  tone  in  a 
consonance.  From  the  possibility  of  the  separate  percep- 
tion of  simultaneous  tones,  Herbart3  came  to  the  conclu- 
sion that  each  musical  tone  must  have  its  distinct  place  in 
the  organ  of  hearing.  At  first  the  anatomical  discoveries 
did  not  give  much  encouragement  to  this  theory.  Since 
the  nerve  endings  in  the  cochlea  were  surrounded  by  water, 
there  was  no  support  whatever  for  this  would-be  anal- 
ogy between  nerve-fibres  and  stretched  elastic  fibres.  But 
purely  psychological  doubts  were  also  raised.  From  the 
supposition  of  a specific  excitability  of  the  fibres  there  would 
follow  as  a conclusion  that  there  must  exist  an  infinite 
number  of  fibres;  and,  besides  this,  simultaneous  excitations 
would  be  separated  in  space  in  different  parts  of  the  organ. 
This  was  a succinct  expression  of  that  nativism  which  had 
been  dominant  since  the  time  of  Muller.4  The  arguments  of 
the  physiologist  Harless5  rest  upon  a very  insecure  physiol og- 

1 Physische  Ursachen  des  Wahren,  1774,  p.  109. 

2 De  aquceductibus  auris  humanoe  internal,  Naples,  1760. 

3 Lehrbuch  zur  Psychologie,  § 72. 

4 Cf.  pp.  326/.  See  also  the  article  “Horen,”  by  Harless,  in  Wagner’s 
Handworterbuch  der  Physiologie,  IV,  1853,  p.  311. 

5 Op.  cit.,  p.  435. 


THEORIES  OF  SENSATION 


299 


ical  foundation.  He  questions  the  ability  of  the  ear  to 
perceive  several  tones  separately  and  simultaneously.  The 
ear  is  not  able  to  recognize  two  simultaneous  tones  as 
separate  individual  sensations  except  in  the  same  sense  as 
the  artist  may  recognize  the  principal  colors  in  a mixture 
in  spite  of  the  fact  that  the  impressions  coming  from  it 
may  be  perfectly  fused  together.  This  line  of  thought  is  a 
capital  example  to  show  how  often  there  may  remain  hid- 
den for  a long  time  something  that  we  take  for  granted  as 
an  immediate  result  of  introspection.  The  difference  be- 
tween hearing  a certain  tone  in  a combination  of  tones  and 
of  analyzing  a color-mixture  into  its  component  parts  is  for 
us  so  striking  that  the  analogy  used  by  Harless  appears  ex- 
tremely strange. 

A change  was  made  in  the  direction  taken  by  the  theories 
of  audition  as  soon  as  the  results  of  anatomical  investigation 
came  to  the  aid  of  the  results  already  obtained  by  mathe- 
matical analysis.  Seebeck  proved  that  a laminar  elastic 
body  only  took  up  out  of  a complex  vibration  those  par- 
tial vibrations  which  came  near  to  its  own  vibration  fre- 
quency. Anatomical  investigation  then  discovered  a special 
appendage  to  the  nerve  terminals,  the  so-called  organ  of 
Corti,  which  could  easily  be  supposed  to  be  equipped  with 
special  elastic  properties. 

( b ) The  Theory  of  Resonance 

Following  along  these  lines  Helmholtz  arrived  at  a me- 
chanical theory  of  hearing  in  his  Lehre  von  den  Tonempfin- 
dungen  (1862). 1 He  started  with  the  presupposition  that 
the  ear  is  able  to  analyze  complex  vibrations  into  simple 
pendular  vibrations.  The  combination  out  of  many  sepa- 

1 [English  translation,  by  A.  J.  Ellis,  Sensations  of  Tone,  3d  ed.«  Lon- 
don, 1895.  Trs.] 


300 


HISTORY  OF  PSYCHOLOGY 


rate  vibrations  of  a clang  produced  by  a musical  instrument 
comes  to  our  perception  as  a clang  by  means  of  the  ear. 
In  reality  the  movement  of  the  particles  of  air  is  always 
simple,  brought  about  by  a single  cause.  The  only  analogy 
found  in  nature  for  such  an  analysis  of  periodic  movements 
into  simple  ones  is  In  the  phenomenon  of  sympathetic  vi- 
bration. Under  the  influence  of  a powerful  clang  only  those 
strings  of  a piano,  with  its  damper  raised,  vibrate  sym- 
pathetically which  correspond  to  the  simple  tones  con- 
tained in  the  clang.  If,  now,  each  string  of  the  piano  were 
connected  with  a nerve-fibre,  then  each  clang,  precisely  as 
it  happens  in  the  ear,  would  produce  a whole  series  of  sensa- 
tions corresponding  to  simple  pendular  vibrations. 

Some  such  arrangement  as  this  Helmholtz  really  believed 
he  had  found  in  the  inner  ear.  The  ends  of  the  auditory 
nerve  are  everywhere  connected  with  a special  auxiliary 
apparatus  which,  vibrating  sympathetically  with  the  out- 
side vibrations,  very  probably  shakes  and  stimulates  the 
nerve  mass. 

After  the  problem  of  audition  had  thus  been  transformed 
into  a mechanical  one  there  arose  the  opportunity  for 
the  use  of  mathematical  assistance  which  Helmholtz  could 
manage  with  a master-hand.  The  mechanics  of  resonance 
show,  first  of  all,  that  bodies  which  sound  for  a long  time, 
e.  g.,  tuning-forks,  resonate  strongly,  because  they  sum  up 
for  a long  time  the  really  weak  thrusts  and  pulls  of  the 
sound-waves.  But  there  must  exist  the  greatest  possible 
correspondence  between  the  fundamental  tone  of  the  body 
in  question  and  the  stimulus  tone.  If,  however,  we  take 
bodies  in  which  the  sound  dies  down  rapidly,  e.  g.,  tightly 
stretched  membranes  or  thin,  light  strings,  then  we  find  that 
their  resonance  is  not  so  restricted  to  a definite  periodic 
vibration  of  the  stimulus  tone.  For  if  a sounding  body 
comes  to  rest  after,  say,  ten  vibrations,  it  is  not  so  impor- 


THEORIES  OF  SENSATION 


301 


tant  that  new  shocks  which  it  receives  after  this  period 
should  correspond  perfectly  with  the  period  of  the  former 
shocks. 

For  this  relationship  Helmholtz  brought  forward  a 
mathematical  theory  which  does  not  depend  upon  the 
nature  of  the  resonating  body.  Let  x be  the  distance  of 
a body  m from  its  position  of  equilibrium,  and  — a2x  the 
elastic  force.  Now,  let  a periodic  force,  A sin  nt,  act,  and 
also  a force  checking  the  vibrations,  the  intensity  of  which 

is  proportional  to  the  velocity,  i.  e.,  — 62 —.  Then  the 


dt 


equation  for  the  movement  is: 


d2x  dx 

m — — = — ora— o2  — — I -A  sin  nt. 
dt2  dt 


From  the  integral  of  this  equation  Helmholtz  was  able  to 
draw  up  a table  which  would  show  after  how  many  vibra- 
tions the  intensity  of  a freely  vibrating  body  would  be  re- 
duced to  a tenth  for  determined  differences  between  the 
specific  tones  of  a stimulating  and  a resonating  body,  by 
means  of  which  the  intensity  of  perfect  resonance  would 
be  reduced  to  a tenth.  For  example,  a body  the  resonance 
vibration  of  which  is  reduced  to  a tenth  by  a difference  of 
an  eighth  of  a tone  reaches,  when  freely  vibrating,  a tenth 
of  its  vibration  intensity  after  38  vibrations;  whereas  for 
a body  that  requires  a difference  of  two  tones  in  order  to 
resonate  as  much  less,  the  second  phenomenon  will  occur 
already  after  2.37  vibrations.  These  figures  become  of  some 
importance  when  considering  the  so-called  trill  threshold. 
Trills  of  about  eight  beats  per  second  can  be  obtained  at 
almost  every  part  of  the  scale.  They  are,  however,  not 
everywhere  equally  plain,  for  in  the  bass  they  become  in- 
distinct by  running  together.  If  now  the  upper  threshold 
of  the  velocity  of  the  trills  is  conditioned  by  the  after  vi- 


302 


HISTORY  OF  PSYCHOLOGY 


bration  of  the  receiving  fibres,  then  in  the  light  of  Helm- 
holtz’s theory  this  fact  would  be  a proof  that  it  must  be 
different  parts  of  the  ear  that  are  made  to  vibrate  by  dif- 
ferent tones.  For  if  the  ear  were  to  vibrate  as  a whole 
and  be  capable  of  a noticeable  after  vibration,  it  would  do 
the  latter  in  its  own  specific  vibration  period,  which  would 
be  absolutely  independent  of  the  period  of  vibration  of  the 
primary  exciting  tone.  In  such  a case  not  only  would  the 
trill  threshold  be  everywhere  equally  high,  but  there  would 
also  be  mixed  with  the  two  tones  a third  tone  which  be- 
longed to  the  ear.  The  result,  therefore,  would  be  quite 
different  from  what  is  actually  observed. 

What  parts  in  the  ear  actually  vibrate  in  sympathy  with 
the  separate  tones  cannot  be  definitely  stated.  At  first 
Helmholtz  supposed  that  the  varying  firmness  and  elas- 
ticity of  the  rods  of  Corti  were  the  reason  for  the  varying 
pitch.  After  Hensen’s1  measurements  of  the  dimensions 
of  the  basilar  membrane,  and  the  observations  of  C.  Hasse 
that  the  bow  of  Corti  is  wanting  in  birds  and  amphibia,  it 
became  more  natural  .to  suppose  that  the  pitch  depended 
upon  the  varying  breadth  of  the  basilar  membrane.  The 
number  of  outer  fibres  in  the  cochlea  amounts,  according 
to  Waldeyer,  to  about  4,500.  With  a medium  difference- 
threshold  of  0.5  vibrations  which  increases  decidedly  as  it 
approaches  the  limits  of  the  musical  scale,  this  number  of 
fibres  would  be  fully  sufficient  to  account  for  distinguish- 
able differences  in  pitch.  Any  number  of  other  differences 
in  pitch  could  also  be  perceived  by  this  theoretical  arrange- 
ment. For  a tone  lying  between  two  neighboring  rods  of 
Corti  would  set  them  both  vibrating  sympathetically,  but 
that  rod  would  vibrate  more  strongly  which  was  more  per- 
fectly attuned  to  the  tone  in  question.  The  least  percep- 
tible difference  in  pitch  would  then  be  dependent  upon  the 
delicacy  with  which  the  degree  of  excitation  of  these  two 
1 Zeitschr.  f.  wissensch.  Zool.,  Bd.  XIII,  p.  492. 


THEORIES  OF  SENSATION 


303 


nerve-fibres  could  be  compared.  This  theory  also  explains 
the  fact  that  our  sensation  increases  continuously  with  a 
continuous  increase  in  pitch,  as,  of  course,  must  be  the  case 
if  only  one  rod  of  Corti  is  set  into  sympathetic  vibration  at 
a time. 

The  sensation  of  tones  of  different  pitch  is  thus  a sensa- 
tion in  different  nerve-fibres.  From  this  there  also  follows 
directly  an  explanation  of  timbre  wThich  depends  upon  the 
fact  that  a clang,  besides  setting  into  vibration  the  particu- 
lar rod  of  Corti  corresponding  to  its  fundamental,  causes 
vibration  in  a number  of  others,  i.  e.,  stimulates  sensations 
in  many  different  groups  of  nerve-fibres.  The  resonance 
theory  also  explained  in  general  the  phenomenon  of  clang 
analysis  as  long  as  the  vibrating  movements  of  the  air  and 
other  elastic  bodies  arising  out  of  several  simultaneous 
sources  of  sound  are  the  sum  of  the  separate  movements 
which  the  separate  sources  of  sound  produce.  This  law, 
however,  has  exact  validity  only  for  infinitely  small  vibra- 
tions. The  totality  of  phenomena,  which  arise  from  the  fact 
that  the  real  vibrations  are  very  small  but  still  not  infinitely 
small,  was  arrived  at  by  Helmholtz1  by  means  of  mathe- 
matics. One  set  of  such  phenomena  are  the  combination- 
tones,  which  Sorge  had  called  attention  to  as  far  back  as 
1740  in  his  Vorgemach  musikalischer  Komposition.  Of 
these  combination-tones  the  objective  ones  that  are  known 
to  take  place  as  vibrations  in  the  air  outside  the  ear  come 
under  the  ordinary  interpretation.  The  subjective  combi- 
nation-tones, however,  must  arise  somewhere  in  the  outer 
parts  of  the  ear  between  the  tympanum  and  the  resonance 
apparatus.  In  the  asymmetrical  setting  of  the  tympanum 
and  in  the  loose  connection  of  the  malleus  and  incus  at  the 
joint  Helmholtz  saw  more  than  sufficient  cause  for  such 
deviations  from  the  simple  laws  of  vibration. 

1 “ Uber  Kombinationstone,”  Poggendorfs  Annalen,  Bd.  XCIX,  p.497. 


304 


HISTORY  OF  PSYCHOLOGY 


(c)  Further  Development  of  the  Resonance  Hypothesis 

Since  the  days  of  Helmholtz  several  investigators,  al- 
though acknowledging  the  mechanical  processes  of  sym- 
pathetic vibration  as  giving  the  best  all-round  picture  of 
the  hearing  process,  nevertheless  show  great  hesitation  in 
accepting  it  as  final  and  comprehensive.  Hensen1  pointed 
out  that  it  would  be  the  business  of  future  investigations 
to  search  for  a series  of  nerve  processes  which  were  tuned 
down  with  a kind  of  damper  to  the  series  of  tones  that 
we  are  able  to  hear.  Besides  that  it  might  also  be  neces- 
sary to  search  for  another  apparatus  which  would  bring  to 
perception  such  phenomena  as  beats. 

L.  Hermann2  arrived  at  a considerable  modification  of 
the  resonance  hypothesis  by  starting  with  the  idea  that  each 
kind  of  period,  including  that  of  the  rise  and  fall  of  a tone 
intensity,  would  be  sensed  as  a tone  as  long  as  its  frequency 
came  within  the  range  of  our  tone  sensations.3  R.  Koenig4 
had  already  made  fairly  accurate  observations  on  the  phe- 
nomena appearing  during  the  simultaneous  sounding  of  two 
or  more  tones.  He  traced  these  back  to  the  beats  of  the  pri- 
mary tones,  and  by  doing  this  returned  to  the  explanation 
that  had  been  first  given  by  Lagrange5  for  difference-tones, 
independent  of  any  theory  of  hearing.  Such  an  explanation 
of  difference-tones,  which  is  quite  similar  to  Young’s,  con- 
tradicts, however,  the  principles  of  the  Helmholtz  theory  of 
resonance;  for  two  simultaneous  simple  tones  affect  only 
the  resonators  corresponding  to  their  vibration  period.  A 
third  resonator,  whose  vibration  period  might  correspond 

1 Hermann’s  Handbuch  der  Physiologie,  III,  2,  1880,  p.  99. 

2 Pflug.  Arch.,  Bd.  XLIX,  1891,  p.  499. 

3 Pflug.  Arch.,  Bd.  LVI,  1895,  p.  467. 

4 Poggend.  Ann.,  Bd.  CLVII,  1876,  p.  177. 

8 Misc.  Soc.  Taur.,  1795. 


THEORIES  OF  SENSATION 


305 


to  the  beat  period  of  the  two  primary  tones,  could  not  pos- 
sibly be  affected  by  these. 

Besides  this,  the  fact  was  also  brought  forward  against 
Helmholtz’s  conception  of  combination-tones  that  they  ap- 
pear very  clearly  with  a moderate  intensity  of  the  primary 
tones,  e.  g.,  during  the  dying  down  of  tuning-forks.  The 
extent  of  their  audibility  was  also  restricted.  Koenig  could 
testify  with  certainty  only  to  the  existence  of  difference- 
tones  if  the  difference  between  the  primary  tones  was  within 
half  an  octave.1  Besides  this,  Voigt2  formulated  the  mathe- 
matical theory  for  the  phenomena  that  arise  out  of  the 
sounding  together  of  two  tones,  without  having  to  presup- 
pose, with  Helmholtz,  a deviation  from  the  linear  laws  of 
sound.  In  the  periodic  maxima  of  the  resulting  vibration, 
which,  in  conformity  with  the  older  beat-tone  theory,  are 
bound  to  cause  a tone  sensation,  he  was  able  to  represent 
not  only  Helmholtz’s  but  also  Koenig’s  tones.  This  proof 
of  Voigt’s  also  increased  in  importance  because  Hermann 
emphasized  the  special  conditions  of  the  deductions  of  Helm- 
holtz. For  he  not  only  neglected  the  higher  powers  of  the 
amplitude  of  the  difference-tones,  but  also  made  the  elastic 
force  of  the  reaction  dependent  upon  the  elongation  x and 
x 2,  and  thereby  introduced  an  asymmetrical  elasticity.  With 
the  physically  simpler  hypothesis  of  a non-linear  but  still 
a symmetrical  elasticity  the  velocity  must  be  an  uneven 
function  of  the  elongation.  Then  we  get  the  ternary,  qui- 
nary, etc.,  combination-tones,  and  not  the  binary,  which 
correspond  to  the  difference-tones.3 

For  such  reasons  Hermann  returned  to  an  explanation 
of  difference-tones  out  of  beats.  He  set  resonators  sounding 
by  means  of  air  vibrations.  Now,  these  resonators  affect 

1 Quelques  experiences  d’acoustique,  1882,  pp.  87  ff. 

2 Nachr.  v.  d.  Gottinger  Gesellsch.  d.  IFiss.,  1890,  No.  5,  p.  159. 

3 Op.  cit.,  p.  507. 


306 


HISTORY  OF  PSYCHOLOGY 


the  nerve-fibres  through  the  mediation  of  nerve-cells,  which 
are,  as  it  were,  attuned  to  their  own  specific  period,  and 
which,  because  of  their  elective  excitability  for  a specific 
frequency  of  stimulations,  were  called  by  him  counting-cells. 
The  decisive  point  in  Hermann’s  theory  is  the  supposition 
that  these  counting-cells  stand  in  functional  relationship  to 
all  resonators.  Now,  if  the  tone  n is  interrupted  v times, 
it  will  stimulate  the  counting-cell  v,  and  this  will  be  heard 
as  an  interruption-tone.  Difference-tones  arise  from  the 
fact  that  the  vibration  resulting  from  two  primary  tones  is 
a vibration  wrhich  approaches  the  arithmetical  mean  of  the 
vibration  periods,  which  rises  and  falls  in  amplitude,  and 
which,  therefore,  immediately  changes  the  phase.  Such  a 
middle  or  mean  tone  can,  according  to  Hermann,  be  heard, 
and  the  difference-tone  is  nothing  else  than  the  interruption- 
tone  of  a middle  tone.  By  this  means  Hermann  avoided 
the  Wundtian  hypothesis  of  direct  stimulation  of  the  audi- 
tory nerve.  With  Helmholtz  the  mechanical  analogy  of  sym- 
pathetic vibration  was  the  determining  factor.  Hermann, 
on  the  other  hand,  in  order  to  picture  the  processes  in  the 
counting-cells,  drew  an  analogy  writh  electrical  processes, 
which  may  likewise  take  place  according  to  the  laws  of  linear 
elasticity.  If  the  state  of  a nervous  organ  oscillates  between 
varying  grades  of  dissimilation  and  assimilation,  we  can  put 
the  D force  proportional  to  the  extent  of  the  deviation  from 
the  A side,  and  conversely.  The  organ  then  oscillates 
isochronically  about  the  state  of  equilibrium  with  a decrease 
in  amplitude  determined  by  the  degree  of  damping. 

Among  the  theories  that  attempt  to  give  a mechanical 
account  of  sound  excitation  without  using  the  facts  of  reso- 
nance, the  most  noteworthy  besides  Meyer’s1  is  the  theory  of 

1 [Max  Meyer,  The  Mechanics  of  the  Inner  Ear,  University  of  Mis- 
souri Studies,  1907.  Arch.  f.  d.  gesamt.  Physiol.,  Bd.  CLIII.  The  fol- 
lowing is  a brief  and  simple  statement  of  his  theory:  “Another  theory 


THEORIES  OF  SENSATION 


307 


R.  Ewald,1  which  represents  a specifically  modern  way  of 
thinking.  Ewald  agrees  with  Mach’s  statement  that  there 
exists  a relation  between  the  problems  of  technology  and 
those  of  physiology,  inasmuch  as  the  former  has  the  task  of 
attaining  certain  ends  with  a free  choice  of  the  means, 
whereas  the  latter  has  to  search  for  the  means  that  have 
really  been  used  for  a definite  purpose.  According  to  Helm- 
holtz’s theory,  the  perception  of  a single  tone  would  be  im- 
possible, because  in  every  case  the  higher  resonators  must 
be  affected  by  a fundamental  tone.  Besides  this,  it  does  not 
give  an  explanation  of  interruption  and  difference  tones,  of 
the  difference  between  tone  and  noise,  or  of  consonance  and 
dissonance.  A purely  psychological  difficulty  also  arises 
from  the  impossibility  of  explaining  the  serial  arrangement 
of  tones,  and  a phylogenetic  difficulty  from  the  uselessness 
of  the  adaptation  of  the  resonance  apparatus  to  specific 
sources  of  sound,  since  these  change  during  development. 
Ewald,  therefore,  returned  to  the  older  view-point  that  the 
apparatus  receiving  the  sound  always  vibrates  as  a whole. 
On  the  basilar  membrane,  in  the  form  of  static  waves, 
sound  pictures  were  supposed  to  arise  which  differed  ac- 
cording to  pitch  and  affected  the  end-organs  of  audition  in 

avoids  these  difficulties  by  merely  assuming  that  the  ribbon-like  par- 
tition of  the  tube  (cochlea),  when  pushed  by  the  fluid,  moves  out  of 
its  normal  position  only  to  a slight  extent  and  then  resists,  and  that, 
therefore,  the  displacement  of  the  partition  must  proceed  along  the 
tube.  If  successive  waves  of  greater  and  lesser  amplitude,  as  we  find 
them  in  every  compound  sound,  act  upon  the  tympanum  and  indi- 
rectly upon  the  fluid  in  the  tube,  the  displacement  of  the  partition 
must  proceed  along  the  tube,  now  farther,  now  less  far,  now  again  to 
another  distance,  and  so  on.  Accordingly  one  section  of  the  partition 
is  displaced  more  frequently,  another  less  frequently,  others  with  still 
less  frequencies  in  the  same  unit  of  time.  This  theory  then  makes  the 
hypothesis  that  the  frequency  with  which  each  section  of  the  partition 
is  jerked  back  and  forth  determines  the  pitch  of  a tone  heard,  and  ex- 
plains thus  the  analyzing  power  of  the  ear.”  Ebbinghaus’s  Psychology, 
translated  and  edited  by  Max  Meyer,  1908,  p.  77.  Trs.] 

1 Pfliig.  Arch.,  Bd.  LXXVI,  1899,  p.  147. 


308 


HISTORY  OF  PSYCHOLOGY 


accordance  with  their  spatial  arrangement.  Differences  in 
pitch  were  determined  by  the  distance  between  the  nodal 
lines  and  by  the  lengths  of  the  separate  wave  valleys.  In 
his  experiments  with  elastic  membranes  stretched  across 
wooden  frames  Ewald  believed  he  had  obtained  an  experi- 
mental foundation  for  his  hypothesis. 

In  spite  of  all  this,  the  point  of  view  established  by  Helm- 
holtz still  remains  the  dominant  one  in  physiological  and 
psychological  acoustics  at  the  present  time.  Even  his  theory 
of  combination-tones,  which  seemed  to  be  the  most  insecure, 
has  quite  recently  been  supported  by  the  investigations  of 
K.  L.  Schaefer  and  Waetzmann.1  These  investigations  deal 
with  the  intensity  of  difference-tones,  which,  according  to 
Helmholtz’s  theory,  should  be  proportional  to  the  product 
of  the  amplitudes  of  the  primary  tones.  No  other  psycho- 
logical theory  can  compare  with  the  resonance  theory  in 
regard  to  the  fortunate  position  it  has  maintained  in  spite 
of  all  hostile  attacks. 

(i d ) Consonance  Theories 

About  twenty-five  hundred  years  ago  Pythagoras  gave 
science  this  riddle  to  solve:  In  what  relation  does  conso- 
nance stand  to  the  relations  between  small  whole  numbers?2 
But  it  was  not  until  Fourier  formulated  his  theorem  and  ap- 
plied it  to  the  analysis  of  tones  made  by  the  ear  that  the 
fundamental  question  was  made  clear.  This  theorem  showed 
how  any  periodically  changing  value,  however  constituted, 
could  be  expressed  as  the  sum  of  simple  periodic  values, 
i.  e.,  by  means  of  the  sine  and  cosine  of  the  variable  quan- 
tities. The  Pythagoreans  expected  to  find  the  number  re- 

1 Cf.  Ann.  d.  Phys.,  1909,  Bd.  XLVIII,  p.  1067,  and  literature  cited 
there. 

2 Cf.  Helmholtz,  Lehre  von  den  Tonempfindungen,  4 Aufl.,  1877,  p.  374, 


THEORIES  OF  SENSATION 


309 


lations,  which  exist  between  the  seven  tones  of  the  diatonic 
scale,  in  the  distances  of  the  planets  from  the  cosmic  fire. 
The  speculations  of  the  Chinese  also  stretch  back  to  the 
earliest  period.  Tso-kiu-ming,  the  friend  of  Confucius,  set 
up  an  analogy  between  the  five  tones  of  the  old  Chinese 
scale  and  the  five  elements — water,  fire,  wood,  metal,  and 
earth.  Later  on  the  twelve  half  tones  of  the  octave  were 
supposed  to  correspond  to  the  twelve  months  of  the  year. 
The  musical  literature  of  the  Arabs  is  rich  in  analogies  be- 
tween the  consonant  intervals  and  the  elements,  the  tem- 
peraments and  the  constellations.  In  the  Middle  Ages  the 
harmony  of  the  spheres  played  a great  part.  Athanasius 
Kircher  conceived  of  a music  produced  by  the  macrocosm 
and  the  microcosm. 

In  contradistinction  to  such  fantastic  analogies  there 
arose  gradually  the  idea  that  it  was  the  duty  of  a real  the- 
ory of  consonance  to  explain  the  affective  characteristics  of 
specific  tone  combinations  in  psychological  or  physiological 
terms.  The  usual  designation  of  consonance  as  an  agree- 
able and  of  dissonance  as  a disagreeable  tone  combination 
cannot  in  this  sense  be  called  a theory.  Besides  this  it  is 
easy  to  show  that  the  affective  impression  of  isolated  in- 
tervals has  changed  considerably  even  within  the  course  of 
history.  The  ancients  called  the  octave  the  most  beautiful 
consonance;  the  monks  of  the  ninth  century  praised  the  fifth 
as  the  sweetest  of  all  combinations;  whereas  at  the  present 
day  we  are  inclined  to  give  the  first  place  to  the  major  third. 

The  psychological  problem  implicit  in  the  relation  of  con- 
sonance to  whole  numbers  was  first  treated  by  the  mathe- 
matician L.  Euler.1  From  contemporary  aesthetics  he  bor- 
rowed the  principle  that  an  object  is  pleasing  if  it  shows 
some  definite  rule  as  regards  its  arrangement.  A combina- 
tion of  tones  will  please  us  the  more  the  easier  we  are  able 
1 Tentamen  novae  theories  Musicce,  1739. 


310 


HISTORY  OF  PSYCHOLOGY 


to  find  the  law  of  its  arrangement,  which  is  expressed  as 
regards  time  in  its  rhythm  and  as  regards  pitch  in  its  in- 
tervals. Just  as  we  easily  notice  the  regularity  of  a rhyth- 
mical period  in  which  two,  three,  or  four  like  notes  of  the 
one  voice  are  apportioned  to  one,  two,  or  three  notes  of  the 
other,  in  the  same  way  we  can  easily  comprehend  it  when 
two,  three,  or  four  vibrations  of  a tone  correspond  to  one, 
two,  or  three  of  another.  And  this  is  more  pleasing  than 
if  the  relation  of  the  vibrations  can  be  expressed  only  by 
large  numbers.  As  to  the  psychological  processes,  however, 
by  which  the  number  relation  of  the  two  tones  sounded 
together  was  comprehended,  Euler  was  unable  to  give  any 
explanation.  The  psychological  facts  appeared  unrelated 
alongside  of  the  physical,  and  the  metaphysical  soul  force 
functioned  as  a go-between  in  just  as  unsatisfactory  a man- 
ner as  it  did  with  Leibniz,  who  supposed  the  soul  to  carry 
out  an  unconscious  calculation  of  the  number  of  vibra- 
tions.1 

The  empirical  missing  links  were  found  in  the  nineteenth 
century  in  the  unconscious  perception  of  the  vibration 
rhythm.2  This  theory  has  in  modern  times  found  its  best 
expression  in  Th.  Lipps.3  Although  tone  sensations  make  up 
a continuous  undifferentiated  series,  yet  they  are  in  origin 
discontinuous  phenomena,  the  rhythm  of  which  is  carried 
over  to  the  soul  and  to  its  excitations.  The  rhythms  of 
these  psychic  excitations,  which  underlie  our  conscious  tone 
sensations,  are  friendly  or  support  each  other  if  they  fit 
into  each  other  in  a simple  manner,  but  they  are  antago- 
nistic if  they  do  not  fit  together  but  cross  and  oppose  each 
other.  Now,  this  fitting  together  or  support  of  one  psychic 
content  by  another  gives  rise  to  pleasure  and  the  opposi- 

1 Principes  de  la  nature  et  de  la  grdce,  1718,  17. 

2 F.  W.  Opelt,  Allgemeine  Theorie  der  Musik  auf  den  Rhythmics  der 
Klangwellenimpulse  gegriindet,  1852. 

3 Psychologische  Studien,  1885,  pp.  92  JJ. 


THEORIES  OF  SENSATION 


311 


tion  or  inhibition  gives  rise  to  displeasure.  This  principle 
explains  the  affective  states  of  consonance  and  of  dissonance. 

Attempts  to  find  the  missing  link  between  the  physical 
and  the  psychological  conditions  in  certain  concomitant 
sense  phenomena  date  back  to  the  eighteenth  century.  As 
far  back  as  1700  the  deaf  Sauveur  explained  dissonance 
by  means  of  the  overtones  which  he  had  discovered.  And 
Esteve  in  1751  derived  consonance  from  coinciding  partial 
tones.  In  a similar  way  Tartini’s  considerations  regarding 
the  reason  of  consonance1  were  based  upon  the  difference- 
tones  discovered  by  himself  and  Romieu  in  1753.  Accord- 
ing to  the  criticism  of  his  contemporaries,  Tartini’s  book  was 
so  obscure  that  no  one  could  really  form  an  opinion  of  this 
matter.  Later  on  overtones  were  again  used  by  Rameau 
and  D’Alembert.2  Since  each  sounding  body  produces  be- 
sides the  fundamental  ( generateur ) also  the  twelfth  and  the 
next  higher  third  as  overtones  (Jiarmoniques) , it  follows  that 
the  major  chord  is  the  most  natural  of  all.  The  minor 
triad  arises  if  we  seek  three  tones  which  have  the  same  over- 
tone, namely,  the  fifth  of  the  first  tone.  This  is,  however, 
not  so  perfect  and  natural.  In  the  way  in  which  it  is  taken 
for  granted  that  the  natural  corresponds  absolutely  with  the 
pleasing  is  mirrored  the  whole  disposition  of  the  age,  which 
was  characterized  by  the  desire  for  a return  to  nature. 
The  historical  importance  of  all  these  attempts  lies  in  the 
fact  that  they  gradually  shifted  the  problem  of  consonance 
from  the  field  of  metaphysics  to  that  of  the  natural  sciences. 

It  was  Helmholtz  who  first  developed  these  beginnings 
into  a real  phonetic  theory.  He  had  analyzed  the  single 
clang  into  its  component  parts  and  had  noted  the  special 
phenomena  arising  in  combinations  of  clangs;  i.  e.,  beats 
and  combination-tones.  Then  he  explained  dissonance  by 

1 Traite  de  VHarmonie,  1754. 

2 Elements  de  Musique  suivant  les  principes  de  M.  Rameau  par  M. 
d'Alembert,  1762. 


312 


HISTORY  OF  PSYCHOLOGY 


means  of  the  beats  arising  from  all  these  component  parts. 
The  psychological  content  of  Helmholtz’s  principle  of  con- 
sonance is  surprisingly  simple.  Those  clangs  are  consonant 
which  continue  alongside  of  each  other  in  an  undisturbed, 
even  flow;  if,  however,  a part  of  the  clang  total  falls  apart 
into  uneven  tone  beats  and  the  compound  clang  becomes 
rough,  there  arises  a dissonance.  The  decisive  character- 
istic is  positive  for  the  dissonance.  Consonances  are  those 
intervals  in  which  such  disturbances  of  sensation  are  want- 
ing. This  union  of  the  feeling  of  unpleasantness  with  the 
roughness  of  the  dissonance  has  first  of  all  a physiological 
basis,  since  any  intermittent  excitation  exerts  a greater 
strain  upon  the  nervous  system  than  an  even,  continuous 
stimulation.  Along  with  this  we  have  also  the  psychological 
peculiarity  that  the  separate  tone  beats  of  a dissonant  com- 
pound clang  form  a confused  tone  mass  which  we  are  un- 
able to  analyze  clearly  into  its  separate  elements.1  This 
psychological  motive  is  clearly  of  an  intellectualistic  charac- 
ter. The  analysis  of  a tone  mass  into  its  component  parts, 
the  counting  of  vibrations,  obviously  presupposes  processes 
that  are  very  nearly  allied  to  intellectual  ones. 

To  this  Helmholtz  joined  a second  principle  that  is  ob- 
tained out  of  the  phenomena  of  the  relation  of  clangs.2  The 
degree  of  the  direct  relationship  of  tones  is  determined  by 
the  number  and  the  intensity  of  the  partial  tones  common 
to  two  fundamental  clangs.  This  relationship  is  not  ap- 
prehended by  means  of  conscious  analysis,  but  rather  is  it 
immediately  perceived  as  a similarity  of  the  clangs,  so  that 
consonance  can  be  called  similarity  produced  by  common 
partial  tones  and  dissonance  as  a want  of  similarity  or  the 
presence  of  a relatively  small  amount  of  similarity.3  The 
first  principle  of  consonance  applied  to  simultaneous  tones, 

1 Lehre  v.  d.  Tonempf.,  4th  ed.,  p.  369.  2 Op.  cit.,  pp.  423,  584. 

3 After  Stumpf,  Beitrdge  zur  Akustik  und  Musikwissenschaft,  H.  1, 

1889,  p.  3. 


THEORIES  OF  SENSATION 


313 


whereas  the  second  principle  is  of  significance  only  in  regard 
to  successive  tones.  For  in  the  first  case  a common  par- 
tial tone  would  be  only  a third  weaker  tone,  which  could 
not  be  heard  as  common  to  the  two  strong  tones.  It  is 
strange  that  Helmholtz  nowThere  calls  attention  to  this  du- 
plicity in  his  theory  of  consonance. 

In  lieu  of  all  these  theories  of  consonance  C.  Stumpf  for- 
mulated the  so-called  theory  of  fusion.  Since  the  difference 
between  consonant  and  dissonant  tones  can  lie  neither  in 
unconscious  functions  nor  yet  in  the  feelings,  wre  must  with 
Helmholtz  seek  this  difference  in  the  region  of  tone  sen- 
sations, not,  however,  in  the  accompanying  overtones  or 
beats  but  rather  in  the  two  tones  themselves.  As  the 
only  characteristic  that  presented  itself  in  this  connection, 
Stumpf1  thought  he  must  take  the  fusion  of  simultaneous 
tones.  This  definition  returns  to  the  original  definitions  of 
the  words  consonance  (crufjLcfiavi'a  — sounding  together)  and 
dissonance  {hafyuvia  = sounding  apart),  and  thereby  cor- 
responds with  the  peculiarity  of  consonance  almost  univer- 
sally emphasized  in  the  ancient  theories  of  consonance,  i.  e., 
that  in  it  there  takes  place  a mixture  of  simultaneous  tones.2 
In  contrast  to  the  striking  affective  impression  of  consonance 
this  characteristic  of  fusion  has  gradually  been  forgotten 
during  succeeding  ages.  In  modern  times  it  has  been  oc- 
casionally mentioned,  as,  for  example,  by  L.  Bendavid,3  the 
writer  on  aesthetics,  who  understood  by  consonances  such 
tones  “in  which  the  ear  imagines  it  hears  only  one  tone 
when  they  are  sounded  simultaneously.” 

An  understanding  of  Stumpfs  definition  of  consonance 

1 This  principle  was  first  formulated  from  his  own  observations  on 
the  piano,  1883;  for  a full  description,  see  “Konsonanz  und  Dissonanz,” 
Beitr.  z.  Akust.  u.  Musikwiss.,  1898. 

2 Cf.  Stumpf,  “Geschichte  des  Konsonanzbegriffs,”  I.  Teil,  Abh.  d. 
Munch.  Akad.,  phil.-hist.  Kl.,  1897. 

3 Versuch  einer  Geschmackslehre,  1799,  p.  435. 


314 


HISTORY  OF  PSYCHOLOGY 


depends  upon  a correct  comprehension  of  his  concept  of 
fusion.  This  is  not  the  same  as  the  old  concept  of  the  unity 
of  consciousness  nor  does  it  correspond  with  not  differen- 
tiating the  tones  in  question;  for  in  this  latter  case  at  the 
very  moment  in  which  wre  differentiate  the  tones  of  a con- 
sonant interval  this  interval  itself  must  of  necessity  become 
a dissonance.  Fusion  can  be  better  described  as  the  join- 
ing together  of  two  contents  of  sensation  into  one  whole, 
or  as  unity,  or  as  the  approach  of  the  complex  clang  to 
unison.  The  psychological  conditions  can  be  supposed  to 
lie  in  the  similarity  of  the  tones,  a fact  that  is,  however, 
mentioned  much  later  than  fusion.1  Such  a similarity  is 
universally  agreed  upon  only  in  the  case  of  the  octave. 
In  the  case  of  the  fifth  most  authors  are  even  inclined  to 
assume  just  the  opposite  relationship.  In  contradistinction 
to  that  similarity  the  degree  of  which  is  measured  by  the 
difference  of  pitch  between  the  tones,  the  similarity  of  con- 
sonant tones  must  denote  a new  characteristic.  Stumpf 
eventually  decided  the  question  in  this  manner  by  suppos- 
ing that  there  exist  two  independent  and  fundamental  re- 
lations between  tones— similarity,  which  depends  upon  the 
difference  between  the  number  of  vibrations,  and  fusion, 
which  depends  upon  the  relations  between  the  number  of 
vibrations.  Fusion  can  be  explained  only  by  reference  to 
physiological  conditions.  At  the  simultaneous  sounding  of 
two  tones  having  a simple  relation  between  their  vibration 
periods,  there  take  place  in  the  brain  processes  more  nearly 
allied  to  each  other  than  would  be  the  case  with  vibration 
periods  not  making  such  simple  proportion.  These  simple 
relations  are  supposed  to  form  a special  kind  of  union  which 
Stumpf  called  specific  synergy. 

In  more  recent  times  F.  Krueger,  from  his  observations  on 

1 Cf.  Stumpf,  “ Die  pseudo-aristotelischen  Probleme  der  Musik,”  Abh. 
d.  Berl.  Akad.,  1897,  pp.  12  /. 


THEORIES  OF  SENSATION 


315 


chords,  came  to  the  conclusion  that  the  coinciding  of  differ- 
ence-tones differentiates  consonant  from  dissonant  intervals 
purely  as  a matter  of  sensation.1  In  the  discussion  with 
Lipps  and  Stumpf2  that  followed,  Krueger  emphasized  the 
series  of  gradations  between  consonance  and  dissonance,  in 
the  middle  of  which  series  he  placed  the  neutral  sonance. 
The  discussion  also  brought  into  particular  prominence 
certain  principles  of  method  which  carry  us  quite  beyond 
the  immediate  field  of  consonance  problems,  no  matter 
what  is  thought  of  the  explanation  by  difference-tones. 

1 Krueger,  “ Differenztone  und  Konsonanz,”  Arch.  f.  d.  ges.  Psych., 
Bd.  I,  1903,  pp.  205  ff.;  Bd.  II,  pp.  1 ff. 

2 Psijch.  Stud.,  Bd.  I,  pp.  305  ff.;  Bd.  II,  pp.  205  ff.;  Bd.  IV,  pp.  201  ff.; 
Bd.  V,  pp.  294  jf. 


CHAPTER  XI 


THEORIES  OF  SPATIAL  PERCEPTION 

If  we  make  a division  into  simple  sensations,  on  the  one 
hand,  and  sense-perceptions  as  complex  psychical  phenom- 
ena, on  the  other,  we  find  that  among  the  latter  spatial  per- 
ceptions would  only  form  one  group  along  with  many  others; 
e.  g.,  musical  perception  of  clangs  mentioned  above.  In  the 
historical  development,  however,  attempts  to  clear  up  the 
nature  of  the  formation  of  ideas  by  the  help  of  spatial  per- 
ceptions are  considerably  in  the  majority.  Certainly  tem- 
poral ideas  have  from  the  very  beginning  attracted  atten- 
tion to  themselves,  but  the  real  nature  of  the  problem  of 
time  has  only  been  recognized  in  more  recent  times.  In 
those  early  attempts  at  explanation  we  rarely  pass  the  stage 
of  wonder  at  the  mysterious  nature  of  time,  which  no  one 
could  describe  so  emphatically  as  Augustine.1  In  contra- 
distinction to  this,  psychological  attempts  at  a theory  of 
space  stretch  back  to  a much  earlier  period.  Theories  of 
spatial  perception  are,  indeed,  the  typical  examples  of  per- 
ception theories,  which  have  been  contrasted  to  theories  of 
sensation  ever  since  the  concepts  of  sensation  and  per- 
ception began  to  be  distinguished  from  each  other.2 

As  long  as  the  distinction  between  sensation  and  percep- 
tion had  not  been  drawn,  the  only  question  which  received 
consideration  was  the  question  as  to  how  contents  of  the 
outer  world  were  able  to  reach  the  subject.  This  was  the 
standpoint  of  the  early  Greek  natural  philosophers.  The 

1 Confessiones,  1.  XI,  c.  XXVIII.  2 See  p.  271. 

316 


THEORIES  OF  SPATIAL  PERCEPTION 


317 


division  began  to  appear  in  Plato,  who  in  the  Theostetus 
denied  to  the  soul  the  perception  of  the  object  and  of  the 
color  itself;  for  the  idea  of  the  object  arises  only  out  of  a 
judgment  passed  upon  the  colored  content  of  perception. 
Aristotle  touched  a new  side  of  the  problem  when  he  found 
that  certain  qualities,  such  as  motion,  size,  form,  and  num- 
ber, were  common  to  the  content  of  all  or  of  most  sense- 
perception.  After  this  conceptual  division  the  problems  of 
spatial  perception  lay  in  the  hands  of  natural  scientists. 
Even  though  the  very  marked  oppositions  between  nativ- 
ism  and  empiricism  arose  only  within  modern  times,  yet 
they  show  themselves  in  some  special  problems  of  spatial 
perception  at  a very  early  period.  The  sense  preferred  by 
the  older  theories  is  generally  the  visual  sense.  By  means 
of  the  changing  relationship  into  which  spatial  ideas  of  the 
visual  and  tactual  senses  are  brought,  the  above-mentioned 
oppositions  become  more  and  more  explicit. 

i.  The  Natural  Scientists  of  the  Middle  Ages 

The  most  important  contribution  of  the  Middle  Ages  to 
the  theory  of  vision  is  without  doubt  the  Optics  of  Alhacen, 
which  Witelo  translated  from  the  Arabic  in  1269. 1 It  is 
true  that  the  physiological  conditions  of  vision  are  presented 
by  Alhacen  in  the  traditional  manner.  When,  however, 
we  come  to  his  discussion  of  the  content  of  vision  we 
are  surprised  at  his  psychological  insight.  He  first  of  all 
draws  the  distinction  between  superficial  and  definite  seeing 
or  comprehension  ( comprehensio  superficialis  et  certificata) , 
which  corresponds  to  our  distinction  between  direct  and 
indirect  vision.  Movements  about  the  axis  of  vision  are 
required  in  order  to  make  objects  perfectly  perceptible. 
Since  under  changing  conditions  the  same  characteristic 
1 Cf.  Siebeck,  Arch.  f.  Gesch.  d.  Phil.,  II,  1889,  p.  414. 


318 


HISTORY  OF  PSYCHOLOGY 


may  return,  the  visual  sense  is  able  to  recognize  the  simplest 
characteristics  of  objects;  i.  e.,  brightness,  color,  and  posi- 
tion, to  which  may  be  added  distance,  form,  similarity,  etc. 
But  similarity,  for  example,  cannot  alone  be  the  content 
of  sensation,  since,  although  the  form  of  each  object  reaches 
the  organ  of  vision,  a particular  form  of  similarity  is  never 
to  be  found  there.  It  is  much  more  likely  that  the  idea 
of  similarity  arises  only  out  of  the  comparison  of  different 
forms.  In  a corresponding  manner  thinking  ( ratiocinatio ) 
is  taken  up  with  the  recognition  ( cognitio ) of  an  object,  which 
process  is  pictured  as  an  assimilation  of  the  form  of  the  seen 
with  the  memory  image.  By  an  analogous  assimilation  of 
an  object  with  like  objects  arises  the  knowledge  of  kinds 
or  species.  In  this  manner  sensation  is  supplemented,  so 
that  in  the  repeated  perception  of  an  object  a complete 
act  of  perception  is  made  up  of  sensation,  recognition,  and 
discrimination. 

This  demonstration  of  special  psychological  processes  in 
perception  is  certainly  remarkable.  Alhacen  considered  the 
processes  of  perception  as  unconscious  processes.  He  con- 
sidered them  as  paralleled  by  the  unconscious  links  in  the 
process  of  cognition  and  thought  them  to  be  unconscious 
because  of  their  rapidity.  By  doing  this  he  anticipated 
some  of  the  most  important  lines  of  thought  in  modern 
empirical  theories.  The  same  empirical  point  of  view  was 
also  taken  by  Alhacen  in  a series  of  special  problems  dealing 
with  vision.  An  immediate  perception  of  depth  is  possible 
only  if  the  latter  is  not  too  great  and  if  the  eye  can  fol- 
low some  boundary  all  the  way.  Judgment  as  to  the  size 
of  an  object  is  based  upon  the  distance  and  the  angle  of 
vision. 

In  his  explanation  of  the  perception  of  place  Alhacen 
abandons  his  empirical  standpoint  and  goes  over  to  a point 
of  view  which,  in  modern  terminology,  we  would  designate 


THEORIES  OF  SPATIAL  PERCEPTION 


319 


as  nativistic.  Not  only  would  the  form  of  a thing  be  per- 
ceived in  the  eye  but  also  the  place  of  the  organ  upon  which 
the  form  lies.  Such  a change  in  view-point  can  be  observed 
right  into  modern  times.  The  outer  superficial  differences 
between  localization  on  the  flat  field  of  vision  and  the  ap- 
prehension of  depth  impressed  themselves  upon  psycholog- 
ical thought  sooner  than  the  more  hidden  common  character- 
istics, which  occur  in  the  sense-perception  of  both  these 
phenomena  equally. 

Alhaeen  also  made  observations  on  the  temporal  peculi- 
arities of  visual  perception.  Only  in  the  case  of  known  im- 
pressions does  the  perception  take  place  instantly;  in  the 
case  of  strange  or  indistinct  impressions  a noticeable  period 
of  time  elapses  before  their  recognition.  That  a definite 
time  is  always  necessary  is  clear  to  us  from  the  phenomena 
of  color-mixture  with  the  rotating  color- wheel.  This  tem- 
poral course  is  due,  according  to  Alhaeen,  partly  to  peripheral 
causes,  as  we  should  say  to-day;  i.  e.,  the  conduction  of  the 
impression  in  the  nervous  system.  But  besides  this  he 
points  to  psychological  conditions  to  account  for  the  vary- 
ing degrees  of  rapidity  with  which  impressions  come  into 
consciousness,  and  he  tries  to  group  these  under  certain 
general  laws.  Among  various  objects,  that  one  will  be  rec- 
ognized the  soonest  whose  form  shows  the  least  similarity 
to  that  of  the  other  figures.  In  a garden  we  notice  the 
rose  more  quickly  than  the  myrtle.  Furthermore,  the  simple 
is  more  quickly  apprehended  than  the  complex.  We  see, 
first  of  all,  the  surrounding  circle  and  then  the  many-sided 
figure  drawn  within  it.  With  this  Alhaeen  is  touching  upon 
questions  dealing  with  the  theory  of  apperception,  which 
carry  us  far  beyond  the  theory  of  the  formation  of  sense 
percepts.  Last  of  all,  he  tells  us  that  sense  illusions  depend 
upon  sensation,  upon  an  act  of  knowledge,  or  upon  an  act 
of  judgment.  To  the  last  class  belong  the  real  illusions 


320 


HISTORY  OF  PSYCHOLOGY 


of  perception,  such  as  the  illusive  movement  of  the  moon, 
in  which  case  the  unperceived  movement  of  the  clouds  is 
transferred  to  the  moon  because  of  the  lack  of  some  station- 
ary object  for  the  purpose  of  comparison.  In  spite  of  all 
imperfections  Alhacen  has  given  us  a remarkable  sketch  of 
a theory  of  visual  perception,  and  its  attempt  to  give  an 
explanation  of  psychical  processes  distinguishes  it  favorably 
from  the  conception  of  vision  as  a purely  physical  problem, 
a conception  which  at  the  beginning  of  the  new  era  of  the 
natural  sciences  was  the  dominant  one. 

The  newer  observations  seem  at  first  to  confirm  the  old 
theories.1  J.  B.  Porta2  had  described  the  camera  obscura, 
and  although  it  was  only  much  later  that  Scheiner3  made 
the  observation  that  the  picture  on  the  retina  arose  accord- 
ing to  the  same  principle,  yet  it  provided  the  obvious  anal- 
ogy of  a similar  picture  being  produced  in  the  eye  and  so 
appeared  to  prove  the  validity  of  the  old  picture  theory. 
These  new  views  were  carried  over  by  Kepler4  into  physio- 
logical optics.  Brightness  and  color  are  emanations  from 
bodies  possessing  light  or  color,  and  they  cast  a reverse 
picture  on  the  retina  just  in  the  same  way  as  in  the  camera 
obscura.  By  his  geometrical  proof  that  almost  parallel 
rays  of  light  falling  upon  the  pupil  are  brought  to  a focus 
upon  the  retina,  Kepler  disposed  of  the  old  opinion  that  the 
picture  is  produced  upon  the  choroid  or  upon  the  crystal- 
line lens.  The  change  in  accommodation  is  caused  by  the 
changes  in  distance  between  the  crystalline  lens  and  the 
retina.  Besides  this  Kepler  recognized  that  in  the  judgment 
of  the  distance  of  an  object  the  distance  between  the  two 
eyes,  the  so-called  basal  distance,  serves  as  a base-line,  and 

1 Cf.  W.  Wundt,  Beitrage  zur  Theorie  der  Sinneswahrnehmung,  1862, 
pp.  75  ff from  which  some  of  the  following  material  has  been  taken. 

2 Magia  naturalis,  sive  de  miraculis  rerum  naturalium,  Antwerp,  1590. 

3 Oculus,  sive  fundamentum  opticum,  London,  1652,  p.  176. 

4 Astronomice  pars  optica , 1604,  c.  V;  Dioptrice,  1611. 


THEORIES  OF  SPATIAL  PERCEPTION 


321 


therefore  the  most  important  factors  in  the  recognition  of 
depth,  apart  from  the  binocular  parallel  axis,  were  known 
to  him.  In  a most  remarkable  manner  do  his  philosophical 
opinions  come  to  the  surface  in  the  problem  of  upright 
vision,  which  naturally  arose  after  his  discovery  of  the  in- 
verted position  of  the  retinal  image.  The  inversion  of  the 
image,  which  is  projected  in  the  direction  of  the  reaction, 
is  supposed  to  correspond  to  a distinction  that  he  draws 
between  passive  sight  and  active  light  emanation.1 

Kepler’s  most  important  physiological  discovery,  namely, 
that  the  picture  projected  through  the  lens  comes  into  ex- 
istence upon  the  retina,  was  called  in  question  after  later 
observations.  In  1668  Mariotte2  discovered  the  blind-spot, 
sometimes  named  after  himself.  This  discovery  caused  such 
excitement  that  it  had  to  be  demonstrated  even  to  the 
King  of  England.  Since  no  visual  sensation  occurs  at  the 
point  where  the  optic  nerve  enters  the  retina,  Mariotte  con- 
cluded that  it  was  not  the  retina  but  rather  the  choroid  that 
formed  the  sensitive  sheath  of  the  eye.  It  was  almost  a 
hundred  years  later  before  this  dispute  between  the  physiol- 
ogists was  finally  settled  by  Haller,3  by  pointing  out  that 
the  structure  of  the  retina  at  the  blind-spot  differed  from 
that  of  the  rest  of  the  retina.  To  solve  the  psychological 
difficulties  that  still  seemed  to  exist,  Bernoulli4  brought 
forward  the  observation  that  our  attention  is  generally  con- 
centrated upon  objects  seen  in  direct  vision.  He  also  hinted 
that  the  space  in  the  field  of  vision  corresponding  to  the 
part  projected  onto  the  blind-spot  would  be  filled  out  by 
our  imagination. 

Descartes’s  famous  Dioptrik,  which  explains  localization 
on  a plane  surface  of  vision  in  a nativistic  manner,  can  be 

1 Paralip.  ad  Vitellionem,  1604,  p.  169. 

2 Philos.  Transact.,  1668,  t.  II,  p.  668;  t.  IV,  p.  1023. 

3 Element.  Phys.,  t.  V,  p.  477. 

4 Comment.  Academ.  Peirop.,  t.  I,  p.  314. 


322 


HISTORY  OF  PSYCHOLOGY 


looked  upon  as  a fusion  of  the  physiological  knowledge  of 
the  seventeenth  century  with  general  philosophical  opinions. 
The  recognition  of  the  position  of  objects  is  dependent  upon 
the  position  of  the  parts  of  the  brain  at  the  point  where  the 
sensory  nerves  arise,  for  the  soul  at  any  given  moment 
apprehends  the  position  of  all  the  things  which  lie  along 
straight  lines  stretching  from  the  sensory  parts  of  the  body 
to  infinity.  The  optical  inversion  of  the  retinal  image  is 
counteracted  by  a corresponding  inversion  of  the  fibres  of 
the  optic  nerve  in  the  brain,  so  as  to  make  objects  appear 
upright. 

To  explain  perception  of  depth  Descartes  made  use  of  the 
most  important  empirical  factors.  The  changes  in  the  form 
of  the  eye  which  take  place  in  near  and  distant  vision  for 
dioptric  reasons  are  accompanied  by  changes  in  certain 
parts  of  the  brain  by  the  help  of  which  the  soul  perceives 
distance.  Further,  from  the  angle  of  convergence  of  the 
eyes  we  draw  conclusions  as  to  the  distance  of  objects  with 
the  help  of  a kind  of  natural  geometry.  In  a very  clever 
manner  he  applied  his  theories  to  the  explanation  of  optical 
illusions.  We  see  an  object  in  a false  position  because  of 
confusion  of  the  position  of  the  nerves.  We  judge  bright 
objects  to  be  near  because  the  contraction  of  the  pupil 
caused  by  the  intensity  of  the  light  is  connected  with  the 
movement  made  in  the  adaptation  of  the  eye  to  near  vision. 
In  spite  of  all  these  valuable  observations  the  peculiarly 
psychological  processes  seem  to  have  eluded  him,  for  he  re- 
mained too  much  bound  up  in  his  materialistic  conception 
of  the  soul  and  the  old  introspection  psychology. 


2.  Some  Special  Problems 

The  opinions  which  in  modern  times  have  developed  into 
the  sharp  contrasts  of  nativistic  and  empirical  theories 


THEORIES  OF  SPATIAL  PERCEPTION 


323 


showed  themselves  in  the  earlier  days  not  only  in  the 
attempts  to  explain  the  phenomena  of  vision  in  general  but 
also  in  the  treatment  of  certain  special  problems.  The 
general  peculiarities  of  the  organ  of  vision  had  long  been 
known  before  a theoretical  interpretation  of  them  was 
thought  of.  Kepler  was  the  first  to  arrive  at  a correct  gen- 
eral knowledge  of  the  refractive  qualities  of  the  eye.  And 
yet  we  have  reports  as  to  the  use  of  spectacles  long  before 
his  time.  Pliny1  notes  the  fact  that  there  are  concave 
emeralds  that  possess  the  quality  of  gathering  the  sight  to- 
gether, and  probably  a use  of  this  quality  was  made  by  the 
short-sighted  Nero  in  his  custom  of  watching  the  gladia- 
torial combats  through  an  emerald.2  At  the  beginning  of 
the  fourteenth  century  spectacles  were  described  as  the  in- 
vention of  a Florentine  nobleman,  Salvinus  Armatus,  who 
died  in  1317.  In  something  like  the  form  of  eye-glasses 
their  use  soon  became  quite  common.  The  canon  Van  der 
Paele,  in  Jan  van  Eyck’s  triptych  at  Bruges,  is  holding  such 
a pair  of  eye-glasses  in  his  right  hand. 

Among  the  first  purely  psychological  problems  of  visual 
perception  to  be  discussed  is  the  fusion  of  the  images  aris- 
ing in  the  two  eyes.  The  anatomical  hypothesis  that  the 
optic  nerve-fibres  join  together  in  the  required  manner  in 
the  chiasma  is  traceable  to  Galen.  In  principle  Johann 
Muller  seems  to  have  agreed  with  this  hypothesis,  inasmuch 
as  he  also  demanded  an  anatomical  foundation  for  single 
vision.  There  is  a much  greater  variety  of  attempts  to 
come  to  a psychological  understanding  of  single  vision.  Very 
striking  is  Porta’s3  presupposition  that  we  always  see  alter- 
nately with  one  eye  at  a time.  This  idea  was  supported 
later  in  the  eighteenth  century  by  Du  Tour4  because  of  the 
analogy  with  the  phenomenon  of  rivalry  between  the  two 


1 Plinius,  I.  XXXVII,  c.  V. 

3 De  refractione,  1593. 


2 Plinius,  1,  II,  c.  XXXIV. 
4 Acta  Paris.,  1743. 


324 


HISTORY  OF  PSYCHOLOGY 


halves  of  the  field  of  vision.  In  the  relationship  of  this 
hypothesis  to  the  contention  that  only  one  single  content  of 
consciousness  is  present  at  any  given  moment,1  it  is  not  so 
strange  as  it  appears  at  first  sight. 

Much  greater  popularity  was  enjoyed  by  the  intellectu- 
alistic  explanation  that  the  single  percept  arose  out  of  the 
two  retinal  images  by  means  of  a special  act  of  the  un- 
derstanding. Kepler2  seems  to  have  leaned  toward  this 
explanation,  although  he  dismissed  the  problem  of  single 
vision  very  simply  by  supposing  that  we  have  a single 
image  if  the  two  retinse  are  stimulated  in  the  same  man- 
ner and  a double  image  if  they  are  stimulated  in  different 
ways.  His  contemporary,  Aguillonius,3  modified  the  theory 
by  supposing  that  visual  impressions  were  always  projected 
onto  a certain  plane  cutting  through  the  fixation-point,  the 
so-called  horopter.  After  all  these  attempts  at  explanation 
we  come  to  the  formulation  of  a law  for  such  phenomena. 
Johann  Muller  maintained  that  single  and  double  vision 
were  dependent  upon  the  question  as  to  whether  the  im- 
ages fell  upon  the  same  or  upon  different  portions  of  the 
two  retinae.4 

The  oldest  attempts  at  an  explanation  of  depth  seem 
to  arise  from  the  question  as  to  the  apparent  size  of  the 
moon  at  the  horizon  and  at  the  zenith.  This  question  can 
be  followed  through  centuries  of  human  thought.5  Aris- 
totle’s6 explanation  that  the  humid  vapors  in  the  atmos- 
phere produced  an  enlargement  of  the  image  is  one  that 
was  frequently  repeated.  Ptolemy7  (about  150  B.  C.)  also 
conceived  the  refraction  of  the  light  rays  in  the  vapors  of 
the  atmosphere  as  a reason  for  an  objective  enlargement. 
But  besides  this  he  also  pointed  to  the  influence  which  the 

1 See  p.  182.  2 Dioptrice,  Prop.  62. 

3 Opticorum  libri  VI,  Antwerp,  1613.  4 See  below,  p.  327. 

5 Cf.  E.  Reimann,  Zeitschr.  f.  Psych.,  Bd.  30,  1902,  pp.  1 ff. 

6 Problemata,  sect.  XXVI,  Probl.  55.  7 Almagest,  1.  Ill,  c.  3. 


THEORIES  OF  SPATIAL  PERCEPTION  325 

filling  out  of  the  distance  would  have  upon  our  perception 
of  that  distance  and  therewith  upon  the  apparent  size. 
The  Aristotelian  idea  was  refuted  in  the  Middle  Ages  by 
Alhacen.  Then  Vitellio  (1270)  pointed  out  the  changes 
that  the  apparent  form  of  the  celestial  vault  undergoes,  and 
since  that  time  psychological  explanations  have  been  domi- 
nant. Later  on,  however,  Gassendi  maintained  that  the 
moon  appears  larger  when  near  the  horizon,  since  in  this 
position  the  pupils  become  enlarged  because  of  the  weaker 
light.1  Father  Gouye,2  Molyneux,3  and  Samuel  Dunn4 
brought  forward  their  observations  against  the  explanation 
of  the  phenomenon  which  held  that  the  greater  apparent 
distance  of  the  stars  on  the  horizon  was  caused  by  the  illu- 
sion of  filled  space,  and  pointed  out  that  the  illusion  in  re- 
gard to  the  moon  still  remained  even  if  the  other  objects 
were  absent.  A good  orientation  as  to  the  status  of  the 
question  in  the  eighteenth  century  can  be  obtained  in  Smith’s 
Optics  (1738).  In  this  book  he  attacks  Berkeley  and  returns 
to  the  old  explanation  by  the  apparent  form  of  the  celestial 
vault,  the  horizontal  measurement  of  which,  according  to  his 
own  investigations,  is  three  or  four  times  greater  than  the 
vertical.  In  contradistinction  to  the  varied  series  of  such 
attempts  at  explanation,  the  fundamental  fact  of  ordinary 
binocular  perception  of  depth,  i.  e.,  the  difference  of  the 
image  in  the  two  eyes,  a fact  which  was  known  since  the 
time  of  Euclid  by  many  of  the  ancient  opticians,  only  came 
to  be  fully  recognized  in  the  nineteenth  century.  In  ad- 
dition to  the  older  cursory  observations  of  Smith  in  regard 
to  stereoscopic  fusion,  it  was,  above  all,  Wheatstone’s  dis- 
covery of  the  stereoscope  (1833)  that  led  to  a fuller  knowl- 
edge of  such  phenomena. 

1 Opera,  vol.  II,  p.  225. 

2 Memcrires  de  Vacademie  de  Paris,  1700,  p.  11. 

3 Philos.  Transact.,  vol.  I,  p.  221. 

4 Philos.  Transact.,  vol.  LII,  p.  462. 


326 


HISTORY  OF  PSYCHOLOGY 


Last  of  all,  the  development  of  visual  images  after  opera- 
tions on  the  born-blind  played  an  important  part.  This  was 
mostly  interpreted  to  support  the  empirical  point  of  view. 
Molyneux  declared  that  in  such  a case  the  previous  differen- 
tiation arrived  at  by  the  sense  of  touch  between  a ball  and 
a cube  could  not  be  immediately  transferred,  an  opinion 
that  we  also  find  clearly  stated  in  Locke.  The  description 
given  by  Jurin1  (1738)  of  the  origin  of  a differentiation  on 
the  ground  of  a change  in  the  images  according  to  the  angle 
from  which  they  were  seen  was  a common  one  down  to  the 
time  of  Johannes  Muller,  after  which  nativism  successfully 
opposed  these  empirical  lines  of  thought. 

3.  Nativism 

Although  nativistic  elements  are  to  be  found  in  many  of 
the  older  theories,  yet  it  remained  for  the  nineteenth  cen- 
tury to  work  out  coherent  nativistic  theories.  In  the  theory 
of  sense-perception  we  see  very  clearly  the  dependence  of 
the  positive  sciences  upon  philosophy  during  the  first  half 
of  the  nineteenth  century.  The  influence  of  Kant  affected 
not  only  the  philosophers,  for  we  see  Kantian  ideas  find- 
ing their  way  into  the  natural  sciences.  The  nativism  of 
Johannes  Muller,  which  he  applied  only  to  his  theory  of 
vision,  was  very  soon  applied  also  to  the  tactual  sense,  and 
the  theory,  with  many  modifications,  still  has  influence  at 
the  present  day. 

(a)  The  Founding  of  the  Theory  by  Johannes  Muller 

Kant’s  theory  of  the  a priori  character  of  space  was 
transferred  by  Johannes  Muller  to  the  problems  of  sense- 
perception,2  and  he  thereby  gave  modern  nativism  its  au- 

1 Cf.  Smith,  Optics,  Remarks,  p.  27. 

2 Zur  vergleichenden  Physiologic  des  Gesichtssinns  des  Menschen  und 
der  Tiere,  1826. 


THEORIES  OF  SPATIAL  PERCEPTION 


327 


thoritative  form.  He  firmly  maintained  that  the  retina 
senses  itself  as  spread  out  and  that  the  images  upon  its  sur- 
face arrange  themselves  in  two  dimensions.  The  third  di- 
mension, depth,  is  added  by  reason  of  the  experiences  we 
have  from  looking  at  objects  from  different  points  of  view. 
Since  the  latter  depends  upon  some  act  of  judgment,  Muller 
called  it  an  idea  in  contrast  to  the  sensation  which  we  de- 
rive from  a plane  surface.  From  the  study  of  double  images 
he  formulated  the  important  theory  of  identical  retinal 
parts.  Only  impressions  that  fall  on  certain  points  in  both 
eyes  are  referred  to  the  same  point  in  space.  The  crossing 
of  the  optic  nerves  makes  it  possible  for  a single  divided 
nerve-fibre  to  lead  to  such  corresponding  parts  of  the  ret- 
inae. In  the  sensorium  two  such  parts  correspond  to  only 
one  single  part.  The  problem  of  upright  vision  could  give 
this  theory  no  difficulties.  If  we  see  everything  inverted 
then  the  arrangement  of  the  whole  remains  exactly  the 
same  and  the  tactual  sense  makes  its  localizations  agree 
with  the  visual  sense. 

A remarkable  consequence  for  natural  science  that  grew 
out  of  this  theory  is  the  conception  of  an  absolute  physio- 
logical size  of  the  extent  of  the  field  of  vision  determined 
by  the  sensitive  part  of  our  retina.  An  object  lying  im- 
mediately upon  our  retina  would  be  seen  in  its  absolute 
size,  as,  for  example,  in  the  entoptic  perception  of  the 
choroid. 

( b ) Its  Transference  to  the  Sense  of  Touch 

The  different  kinds  of  theories  of  space  can  also  be  dif- 
ferentiated in  a characteristic  manner  by  considering  how 
far  the  view-point  of  a certain  theory  is  made  to  cover  spa- 
tial ideas  arising  from  both  touch  and  vision.  Nativistic 
theories  are,  as  a rule,  more  consistent.  If  spatial  percep- 


328 


HISTORY  OF  PSYCHOLOGY 


tion  is  once  thought  to  be  innate,  then  this  is  shared  equally 
by  the  visual  and  by  the  tactual  sense.  Empirical  theories 
tend,  on  the  whole,  to  give  the  primacy  to  touch  in  the 
sense  that  its  localizations  precede  those  of  the  visual  sense. 
If  our  perception  of  space  is  derived  from  experience,  then 
it  is  easy  for  the  experiences  of  one  sense  to  influence  those 
of  another.  There  has  scarcely  been  an  absolutely  em- 
pirical theory  of  tactual  perception.  The  attempts  to  make 
the  spatial  images  of  the  sense  of  touch  comprehensible 
without  nativistic  presuppositions  really  always  go  over  to 
the  lines  of  thought  involved  in  the  genetic  theories. 

Since  John  Locke  pointed  out  that  the  sense  of  touch, 
because  of  the  peculiar  insistence  of  its  sensations,  gave  us 
an  immediate  idea  of  the  outer  world,  empirical  theories 
immediately  took  advantage  of  this  wonderful  power.  The 
immediate  localizations  of  the  sense  of  touch  served  as  a 
support  to  the  sense  of  sight  in  Berkeley’s  theory  of  per- 
ception, and  Condillac  promoted  the  sense  of  touch  to  the 
only  original  localizing  sense. 

The  turning-point  in  the  theory  of  tactual  perception  is 
characterized  by  the  fact  that  E.  H.  Weber  transferred  the 
modern  concept  of  nativism  into  the  department  which 
his  own  experimental  investigations  had  illuminated  so 
much.  In  1829  he  made  the  discovery  that  two  impressions 
on  the  skin  will  be  clearly  perceived  as  different  only  if  they 
are  separated  from  each  other  by  a sufficiently  large  inter- 
vening space.1  Strikingly  different  values  were  found  for 
this  spatial  threshold  on  different  parts  of  the  body;  on 
the  cheek,  for  example,  it  was  considerably  larger  than  on 
the  lips.  This  difference  can  be  brought  immediately  to 
perception  by  touching  the  cheek  just  in  front  of  the  lobe 
of  the  ear  with  the  two  points  of  a pair  of  compasses  and 
then  by  drawing  them  rapidly  along  the  skin  across  the  cheek 
1 Ann.  anat.  et  physiol,  de  subtilitate  tactus,  1834,  p.  46. 


THEORIES  OF  SPATIAL  PERCEPTION 


329 


until  one  point  rests  on  the  upper  and  one  on  the  lower  lip. 
In  this  case  the  ends  of  the  compass  do  not  seem  to  be 
drawing  two  parallel  lines,  for  they  seem  to  move  apart  as 
the  lips  are  approached.  As  an  explanation  of  this  strik- 
ing phenomenon  Weber  presupposed  that  only  one  sensa- 
tion arises  if  two  similar  impressions  stimulate  the  same 
elementary  nerve-fibre.  Since,  however,  the  total  diam- 
eter of  all  the  nerve-fibres  is  much  smaller  than  the  total 
surface  of  the  skin,  each  elementary  nerve-fibre  must  make 
sensitive  a much  greater  part  of  the  skin  than  the  part  cor- 
responding only  to  its  own  diameter.1 

The  skin  would  seem  to  be  divided  up  into  small,  sensi- 
tive circles  each  of  which  receives  its  sensitivity  from  one 
elementary  nerve-fibre.  Two  simultaneous  impressions  of 
the  same  kind  fuse  together  whenever  they  fall  within  the 
same  circle  of  sensitivity.  In  order  to  be  spatially  dif- 
ferentiated, not  only  must  they  fall  into  two  different  circles 
of  sensitivity  but  there  must  also  lie  between  them  one  or 
more  other  circles  of  sensitivity.  With  this  last  statement 
Weber  avoided  the  objection  later  unjustly  brought  against 
him  by  Kolliker  and  Lotze;  i.  e.,  that  each  circle  of  sensi- 
tivity was  enclosed  within  a narrow  line  possessing  a high 
power  of  differentiation  from  all  the  adjoining  parts.  So 
far,  then,  the  idea  of  a circle  of  sensitivity  was  determined 
in  a purely  anatomical  manner.  Tactual  perceptions  them- 
selves could  become  possible  only  through  experience.  The 
perception  of  supraliminal  distances  was  supposed  to  de- 
pend upon  the  number  of  circles  of  sensitivity  lying  between 
any  two  points.  The  finer  the  spatial  threshold  the 
greater  does  the  distance  appear  to  be,  a postulate  which 
Weber  thought  to  be  proved  by  the  above-mentioned  ex- 
periment with  the  compasses.  In  spite  of  some  concessions 
to  experience,  the  distance  of  two  circles  of  sensitivity  re- 
1 tfber  den  Tastsinn  und  das  Gemeingefiihl,  pp.  526  jf. 


330 


HISTORY  OF  PSYCHOLOGY 


mains  an  absolute  measure  for  our  sense-perception  of  the 
world.  We  must  add  in  conclusion  that  Weber  in  a later 
revision  of  his  theory  explained  the  idea  of  a break  or 
space  between  two  impressions  to  the  want  of  sensation, 
otherwise  generally  occurring,  on  the  intermediate  circles 
of  sensitivity.  He  also  abandoned  the  search  for  a special 
organ  for  the  so-called  spatial  sense.  His  theory,  there- 
fore, sums  up  perfectly  the  position  reached  by  the  investi- 
gations of  his  day. 

■N  (c)  The  Later  Nativistic  Theories 

A more  exact  knowledge  of  different  phenomena  of  bin- 
ocular vision  from  the  middle  of  last  century  onward  made 
a revision  of  Muller’s  opinions  absolutely  necessary.  The 
fact  that  single  vision  is  really  possible  on  non-identical 
points  of  the  retina  had  always  caused  difficulties  and  had 
required  special  auxiliary  hypotheses,  as,  for  example,  the 
one  of  E.  Briicke1  that  fusion  arose  through  the  wandering 
of  the  fixation-point. 

These  attempts  at  explanation  lead  us  back  to  a form  of 
nativism  which  ascribes  to  the  retina  the  innate  capacity  of 
projecting  visual  impressions  in  the  direction  of  their  en- 
trance and  is,  therefore,  customarily  called  the  projection 
theory.  In  its  principles  this  theory  takes  us  back  to 
fairly  old  theories  of  sense-perception,  and  the  statement  of 
it  by  Porterfield2  helps  to  counterbalance  the  empiricism  of 
the  eighteenth  century. 

In  recent  times  this  was  modified  by  A.  Nagel,3  who  made 
both  retinae  project  independently  upon  two  different  spher- 
ical surfaces,  the  intersecting  line  of  which  runs  through  the 
fixation-point.  In  this  way  many  of  the  characteristics  of 

1 Muller’s  Archiv,  1841,  p.  459. 

2 On  the  Eye,  vol.  II,  1759,  p.  285. 

3 Das  Sehen  mit  zwei  Augen,  1861. 


THEORIES  OF  SPATIAL  PERCEPTION 


331 


double  Images  can  be  explained.  Schleiden1  also  supported 
the  projection  theory  inasmuch  as  he  presupposed  an  im- 
mediate perception  of  direction.  The  concept  of  productive 
imagination  used  by  him  leads  one,  however,  far  beyond 
nativistic  theories. 

In  the  endeavor  to  do  justice  to  the  phenomena  of  fu- 
sion of  double  images  and  the  perception  of  depth  from 
the  standpoint  of  a subjective  identity  hypothesis,  Panum2 
was  the  investigator  who  went  furthest.  The  perception  of 
height  and  breadth  depends  upon  an  innate  and  specific 
kind  of  sensation  of  the  relation  between  the  separate  points 
of  the  retina  and  their  projection  lines,  which  sensation 
arises  out  of  the  specific  arrangement  and  quality  of  the  nerve 
elements  of  the  central  optical  region.  Each  point  on  the 
one  retina  has  corresponding  to  it  an  identical  point  on  the 
other  and  besides  that  a corresponding  circle  of  sensitivity. 
With  such  corresponding  points  single  or  double  vision 
arises  according  to  the  relations  existing  between  them. 
The  perception  of  depth  is  based  upon  a sensation  of  the 
binocular  parallel  axes  and  is  supposed  to  arise  from  the 
reciprocal  action  of  the  central  stimulations  produced  by 
the  contours  of  both  the  retinal  images.3 

The  logical  conclusions  of  the  principles  laid  down  by 
Panum  are  met  with  in  the  theory  of  Ewald  Hering.4  From 
the  stimulation  of  a point  on  the  retina  there  arise,  in  ad- 
dition to  the  visual  sensation,  three  kinds  of  spatial  feelings. 
The  first  two  kinds  are  dependent  upon  the  height  and 
breadth  of  the  given  part  of  the  retina;  they  join  together 
for  the  common  field  of  vision  into  a feeling  of  direction  and 
coincide  exactly  for  corresponding  points  of  the  retina.  The 

1 Zur  Theorie  des  Erkennens  durch  den  Gesichtssinn,  1861. 

2 Physiologische  Untersuchung  uber  das  Sehen  mit  zwei  Augen,  1858. 

3 Op.  tit.,  pp.  52,  85  ff. 

4 Beitrage  zur  Physiologie,  1861-4,  and  Hermann’s  Handbuch  d. 
Physiol.,  Ill,  1,  1879,  pp.  343  ff. 


332 


HISTORY  OF  PSYCHOLOGY 


third  spatial  feeling  is  a feeling  of  depth,  which  for  each  two 
identical  retinal  points  takes  on  equal  but  contrary  values 
and  for  symmetrically  placed  positions  equal  and  similar 
values.  Up  to  this  point  the  presuppositions  answer  the 
requirements  which  every  theory  of  spatial  perception  is 
bound  to  meet.  If  instead  of  spatial  feelings  we  substitute 
the  expression  “local  signs,”  this  theory  can  readily  be 
transformed  into  one  of  the  theories  that  we  shall  have  to 
consider  later.  The  further  contention  that  those  stimuli 
which  fall  upon  corresponding  points  always  give  rise  to 
only  one  simple  sensation  is,  to  be  sure,  exclusively  the 
prerogative  of  the  identity  hypothesis.  For  single  vision 
with  disparate  parts  of  the  retina  Hering  gives  the  purely 
psychological  reason  that  in  such  a case  the  practice  and 
training  of  the  attention  necessary  for  the  separation  of 
complex  sensations  is  wanting.  In  the  binocular  fusion  of 
two  impressions  the  total  resulting  sensation  receives  the 
middle  value  of  the  feeling  of  direction  and  of  the  feeling  of 
depth.  In  this  way  the  feelings  of  depth  of  identical  parts 
which  have  equal  but  opposite  values  are  reduced  to  zero. 
All  points  whose  depth  values  have  in  this  way  been  reduced 
to  zero  appear  to  our  immediate  experience  to  lie  upon  a 
plane  surface. 

In  later  theories  these  basic  principles  of  a nativistic 
theory  so  masterfully  sketched  by  Hering  are  all  lost  in  a 
mesh  of  wondrous  hypotheses.  An  example  of  such  an  one 
is  the  theory  of  Hasner,1  which  characteristically  terminates 
in  an  extreme  rationalism.  Perception  and  sensation  both 
stand  on  the  same  level,  but  the  activity  of  the  senses  them- 
selves is  conceived  of  as  a sort  of  mathematical  calculus. 
The  concept  of  red  is  supposed  to  arise  out  of  four  hundred 
and  fifty-two  billions  of  time  intervals  per  second,  including 
certain  wave-lengths  and  duration  of  oscillation.  In  its  ap- 
1 Beitrage  zur  Physiologie  und  Pathologie  des  Auges,  1873. 


THEORIES  OF  SPATIAL  PERCEPTION 


333 


plication  to  visual  perception  this  questionable  principle 
leads  to  a statement  such  as  this : the  number  of  stimulated 
sensitive  elements  in  the  retina  drawn  upon  the  horizontal 
and  vertical  lines  of  vision,  which  are  used  as  the  two  axes, 
yields  the  concept  of  a surface  according  to  definite  mathe- 
matical laws.1  In  contrast  to  this  we  find  a very  cautious 
formulation  of  a nativistic  theory  by  C.  Stumpf.2  Starting 
from  the  standpoint  inherent  in  the  principles  of  Panum 
and  Hering,  he  contented  himself  with  bringing  forward 
the  possibilities  of  sense  development,  among  which  the 
sensational  nature  of  perception  is  conceived  to  be  the  most 
probable.  In  this  respect  his  standpoint  is  characteristic 
of  modern  times,  seen  in  the  cautiousness  practised  in  the 
decision  of  the  ultimate  problems  of  sense-perception. 

We  note  in  this  development  of  the  nativistic  theories  a 
gradual  retreat  of  the  really  nativistic  elements  to  the 
farthest  outposts  of  sense-perception.  The  inevitable  con- 
cessions to  the  influence  of  experience  have  made  it  neces- 
sary to  tear  down  the  rigid  scaffolding  of  the  conventional 
nativism  of  Johann  Muller  and  to  restrict  nativistic  presup- 
positions to  the  always  hypothetical  foundations.  In  con- 
trast to  this  we  see  in  the  empirical  theories  a continually 
increasing  emphasis  and  value  placed  upon  empirical  lines 
of  thought. 

4.  Empiricism 

Empirical  theories  of  space  originally  accompanied  sen- 
sational theories  of  knowledge.  Corresponding  to  the  vari- 
ous motives  that  led  up  to  philosophical  sensationalism  we 
find  that  the  rise  of  empirical  theories  of  space  was  de- 
pendent upon  very  varied  conditions.  The  classical  form  of 
such  a theory  is  to  be  found  in  the  formulation  by  Helm- 
holtz in  the  nineteenth  century. 

1 Op.  dt.,  p.  11. 

2 Tiber  den  psychologischen  Ursprung  der  RaumvorsteUung,  1873. 


334 


HISTORY  OF  PSYCHOLOGY 


(a)  The  Origin  of  Empirical  Theories  of  Space 

There  are  no  systematically  empirical  theories  of  space 
to  speak  of  until  the  time  of  Locke,  whose  doctrine  of 
knowledge  forms  the  philosophical  background  for  these 
theories.  Of  course,  we  can  trace  back  some  beginnings 
to  a much  earlier  period.1  Even  Locke’s  famous  compar- 
ison of  consciousness,  which  has  not  as  yet  received  any 
impressions  from  experience  with  “white  paper  void  of  all 
characters”  ( tabula  rasa),  has  an  ancient  original  in  the 
7 rival-  aypaifios  0f  Alexander  of  Aphrodisias.2  In  mediaeval 
philosophy  the  term  tabula  rasa  became  common,  and  with 
it  Albertus  Magnus  describes  the  attitude  of  receptive  in- 
telligence, which,  like  a polished  and  smooth  slate,  stands 
ready  for  the  reception  of  impressions.  In  his  emphasis 
upon  the  sense  of  touch  Locke  introduced  a thought  that 
became  characteristic  for  nearly  all  modern  empirical  the- 
ories. Formerly  Democritus  had  credited  the  sense  of  touch 
with  a knowledge  of  the  true  being  of  all  things.  With 
Locke  it  is  the  sense  that  recognizes  the  primary  qualities 
as  differentiated  from  the  others.  Many  empirical  charac- 
teristics are  to  be  found  in  the  theory  of  Malebranche,  who 
anticipated  some  of  the  thoughts  of  the  more  influential 
Berkeley  by  trying  to  determine  different  “signs”  for  the 
perception  of  distance,  and  who  characterized  this  sensa- 
tion in  contradistinction  to  the  simple  sensations  as  a com- 
plex sensation  (sensation  composee ).3 

Berkeley,4  however,  was  the  first  to  formulate  a complete 
empirical  theory  in  which  all  localization  by  the  visual 
sense  was  derived  from  the  sense  of  touch.  The  child 

1 See  above,  p.  318. 

2 Cf.  Baeumker,  Arch.  f.  Gesch.  d.  Phil.,  Bd.  XXI,  1908,  p.  296. 

8 Recherche,  1.  I,  c.  VIII,  § 4.  4 Theory  of  Vision,  1709. 


THEORIES  OF  SPATIAL  PERCEPTION 


335 


learns  first  of  all  to  differentiate  between  the  movements  of 
its  own  hands  and  feet.  Simultaneously  with  these  move- 
ments there  takes  place  a visual  sensation  in  the  eye,  and 
from  that  time  on  the  tactual  perceptions  remain  associated 
with  definite  visual  sensations.  If,  now,  a visual  sensation 
stimulates  a particular  part  of  the  retina  without  any  ac' 
companying  tactual  impression  the  child  comes  to  the  con- 
clusion that  the  object  occupies  the  same  place  that  previ- 
ously, say,  its  finger  occupied.  In  this  way  the  separate 
visual  impressions  are  given  a position  in  space;  by  means  of 
the  continual  connection  with  tactual  impressions  percep- 
tions of  extent,  form,  and  the  other  spatial  ideas  come  into 
being. 

In  such  a theory  there  are  recognized  definite  psychical 
processes  in  vision.  Berkeley  himself  did  not  know  what  to 
make  of  them.  All  he  did  was  to  describe  them  in  the  terms 
of  the  old  introspection  psychology  as  processes  of  infer- 
ence that  take  place  so  quickly  that  we  are  not  aware 
of  them  unless  wTe  pay  special  attention  to  them.  From 
this  time  onward  this  empirical  theory  remained  securely 
established  in  British  psychology  as  a true  companion  of 
that  philosophical  empiricism  which  through  the  two  Mills 
and  Alexander  Bain  had  forced  an  entrance  into  modern 
psychology. 


(6)  Helmholtz's  Theory  of  Space 

The  typical  supporter  of  empiricism  in  the  theory  of 
spatial  perception  in  Germany  is  Helmholtz.  According 
to  his  empirical  view  our  sensations  are  signs  for  our  con- 
sciousness, the  significance  of  which  our  reason  has  to  learn. 
The  signs  received  by  the  visual  sense  are  not  only  different 
as  regards  intensity  and  quality,  i.  e.,  as  regards  bright- 
ness and  color,  but  there  also  exists  a difference  dependent 


336 


HISTORY  OF  PSYCHOLOGY 


upon  the  position  on  the  stimulated  retina,  a so-called 
“local  sign.”  Besides  this,  we  feel  the  degree  of  innervation 
that  takes  place  in  the  nerves  moving  the  ocular  muscles, 
and  we  learn  from  experience  what  changes  take  place  in 
the  visual  image  of  an  object  in  accordance  with  the  change 
in  movement.  The  psychical  functions  which  build  up  out 
of  these  signs  our  spatially  arranged  world  were  originally 
considered  by  Helmholtz  as  intellectual  processes.  Later, 
however,  he  reduced  the  much-disputed  unconscious  infer- 
ence to  associative  processes. 

The  mass  of  details  on  which  Helmholtz  used  this  auxili- 
ary hypothesis  is  controlled  by  a few  theoretical  considera- 
tions which  stand  out  with  remarkable  clearness.  Helm- 
holtz started  out  from  a differentiation  between  what  in  the 
perceptions  received  by  the  visual  sense  is  conditioned  di- 
rectly by  sensation  and  what,  on  the  contrary,  is  conditioned 
by  experience  and  practice.  The  memory  images  of  past 
experiences  combine  with  present  sensations  and  produce  a 
perceptual  image  in  which  consciousness  does  not  draw  any 
distinction  between  what  has  been  contributed  by  memory 
and  what  by  present  sensation.  In  order  to  carry  out  this 
distinction,  which  is  fundamental  to  his  theory,  he  starts 
with  this  empirical  postulate,  “ that  no  undoubtedly  present 
experience  can  be  put  aside  or  avoided  by  an  act  of  the  in- 
tellect or  reason.”  From  this  he  concludes  “that  nothing 
in  our  sense-perceptions  can  be  recognized  as  sensation 
which  can  in  the  perceptual  image  be  avoided  or  turned 
into  its  opposite  by  means  of  elements  which  can  be  proved 
to  arise  from  experience.”1  These  view-points  are  of  some 
importance,  even  though  the  cogency  of  the  empirical  ex- 
planations might  singly  be  called  in  question. 

1 Helmholtz,  Physiol.  Opt.,  2d  ed.,  p.  611. 


THEORIES  OF  SPATIAL  PERCEPTION 


337 


5.  The  Genetic  Theories 

The  genetic  theories  developed  out  of  the  endeavor  to 
avoid  the  anticipations  of  nativism  and  to  dispense  with 
the  inductive  conclusions  of  empiricism.  A welcome  means 
for  this  purpose  was  found  in  the  concept  of  association 
along  with  the  addition  of  the  ideational  mechanics  of 
Herbart.  However  unsatisfactory  an  extension  of  this 
concept  to  the  totality  of  psychical  processes  may  be,  it 
certainly  showed  itself  to  be  of  prime  importance  in  the 
theory  of  the  origin  of  sense-perception.  To  Herbart  can 
be  traced  a whole  series  of  fusion  theories,  among  which 
the  oldest  are  generally  those  that  imagine  they  can  dis- 
pense with  any  physiological  aid.  These  purely  psycholog- 
ical theories  tried  to  deduce  the  necessity  for  spatial  ar- 
rangement from  the  nature  of  the  soul  itself  and  the  stream 
of  ideas  and  thereby  to  make  comprehensible  that  de- 
cisive transition  from  the  sphere  of  purely  intensive  states 
into  the  spread-out,  extensive  manifoldness.  Out  of  these 
theories  there  gradually  developed  those  that  accepted  cer- 
tain physiological  preconditions  and  which  we  shall  there- 
fore group  together  under  the  name  of  “ Local  Sign 
Theories.” 

(a)  Herbart’ s Fusion  Theory 

From  the  application  of  his  principles  of  psychical  mech- 
anism to  the  origin  of  spatial  perception  there  arose  for 
Herbart  the  general  outlines  of  a fusion  theory.  His  chief 
argument  against  nativism  is  still  of  metaphysical  origin. 
The  impressions  received  through  the  medium  of  the  eye 
cannot  be  from  the  very  beginning  spatially  arranged, 
because  in  the  unity  of  the  soul  the  sensations  produced  on 
separate  parts  of  the  retina  must  necessarily  at  first  coin- 


338 


HISTORY  OF  PSYCHOLOGY 


cide.  As  soon,  however,  as  the  eye  is  moved  there  occur 
series  of  sensations  which  are  joined  together  with  some 
regularity.  Movement  in  a given  direction  causes  associ- 
ations which  become  active  again  in  movement  in  the  op- 
posite direction.  In  these  series  of  complexes  no  one 
member  can  be  put  into  another  place,  but  any  change 
of  direction  is  possible.1  Such  an  arrangement  of  sensa- 
tions appears  to  us  as  a spatial  arrangement,  and  it  obtains 
its  natural  middle  point  because  of  the  fact  that  the  per- 
cept of  that  which  is  in  the  centre  of  the  field  of  vision  is 
always  characterized  by  the  greatest  strength,  and  it  there- 
fore tends  to  inhibit  the  percepts  of  the  outlying  points. 
Spatial  perception,  therefore,  consists  in  a graded  fusion  of 
one  percept  with  a series  of  other  percepts,  which  fusion 
because  of  its  unnoticeably  short  duration  produces  the  im- 
pression of  a simultaneously  given  manifold. 

In  this  theory  one  of  the  most  important  elements  for 
later  theories  would  appear  to  be  the  emphasis  laid  upon 
the  movements  of  the  eye.  But  we  must  note  the  fact  that 
Herbart  used  this  idea  quite  differently  from  the  way  in 
which  it  was  used  in  the  later  theories  of  fusion.  The 
movement  of  the  eye  of  which  Herbart  speaks  could  be 
perfectly  supplanted  by  a movement  of  the  outer  objects 
if  this  would  be  sure  to  produce  the  same  succession  of 
percepts.  He  is  concerned  only  with  the  relative  shift  in 
position  and  not  with  the  sensations  that  accompany  real 
movements  of  the  eye. 

(b)  Purely  Psychological  Theories 

Herbart’s  fusion  theory  was  converted  into  a purely 
psychological  theory  by  Waitz.2  He  started  with  the  prin- 

1 Psychologie  als  Wissenschaft,  II,  1,  ch.  3,  and  Lehrbuch  z.  Psych.,  II, 
ch.  3. 

2 Lehrbuch  d.  Psychologie  als  Naturwissenschaft,  1849,  §§  20-27. 


THEORIES  OF  SPATIAL  PERCEPTION 


339 


ciple  that  in  the  soul,  because  it  was  an  undivided  entity, 
two  sensations  differing  merely  in  intensity  could  not  exist 
at  the  same  time.  They  would  tend  rather  to  come  into 
opposition  with  each  other,  an  opposition  that  could  not 
be  appeased  by  successive  perception.  This  last  method 
does  not  agree  with  the  way  in  which  sensations  actually 
occur,  and  therefore  another  solution  is  necessary.  The 
soul  is  constrained  to  perceive  the  simultaneously  given 
manifold  spread  out  part  next  to  part,  and  in  this  con- 
straint lies  the  origin  of  our  spatial  percepts.  Similarly, 
there  arises  the  impossibility  of  comprehending  these  states 
existing  next  to  each  other  as  purely  intensive  qualities. 
The  soul  has  to  oppose  them  to  itself  as  foreign  objects  in 
extended  form.  This  thought  seemed  to  be  given  a con- 
crete form  in  certain  optical  phenomena  of  rivalry.  If  two 
colors  are  placed  in  the  field  of  vision,  at  first  both  appear 
confused.  Then  one  or  the  other  seems  to  stand  out  more 
prominently;  i.  e.,  the  sensations  come  into  opposition  with 
each  other  until  eventually  they  both  take  their  proper 
place  side  by  side. 

This  standpoint  was  transcended  by  making  use  of  the 
eye  movements  themselves.  The  idea  was  anticipated  in 
the  little-known  work  of  the  physiologist  Steinbuch.1  But 
more  influential  than  this  were  the  theories  of  George,2  who 
gave  to  the  very  movement  of  the  organ  a part  in  the  pro- 
duction of  spatial  perception.  It  is  only  when  tactual 
sensations  of  the  skin  are  combined  with  those  of  movement 
that  we  are  able  to  have,  in  the  reflection  based  upon  this, 
a spatial  disposition  of  sensations.  To  carry  this  thought 
further  it  was  absolutely  necessary  to  have  an  exact  analysis 
of  the  sensations  arising  through  movement.  George  spoke 
simply  of  movement  in  general  and  approached  empiricism 

1 Beitrag  zur  Physiologie  der  Sinne,  1811. 

2 Lehrb.  d.  Psychol.,  1854.  Die  fiinf  Sinne,  1846,  p.  235. 


340 


HISTORY  OF  PSYCHOLOGY 


very  closely  in  his  presupposition  of  a logical  elaboration  of 
the  experiences  obtained  from  movement.  The  analysis  of 
the  complex  of  experiences  occurring  during  a movement  led 
investigators  to  recognize  a series  of  sensations  of  strain 
graded  as  to  intensity  which  are  accompanied  by  temporal 
percepts.  The  way  in  which  spatial  perception  separates 
itself  out  of  this  complex  was  shown  in  the  theory  of  Alex- 
ander Bain,1  the  most  perfect  of  the  purely  psychological 
theories.  The  spatial  percept  can  separate  itself  from  the 
temporal  because  the  same  differences  in  the  percept  which 
are  necessary  to  measure  a spatial  distance  may  be  ex- 
perienced within  different  periods  of  time  according  to  the 
velocity  of  the  movement.  Beside  this  the  arrangement  of 
spatially  indicated  impressions  becomes  independent  of  the 
order  of  their  succession,  inasmuch  as  we  may  comprehend 
successively  a series  of  objects  at  varying  velocities. 

(c)  The  Local  Sign  Theories 

A new  way  to  the  localization  of  sensations  was  opened 
by  Lotze  with  his  concept  of  the  “local  sign.”  Later  on  his 
theory  developed  partly  in  a physiological  and  partly  in  a 
psychological  direction.  All  these  later  forms  of  the  theory 
of  local  signs  have  a common  point  of  contrast  to  the  purely 
psychological  theories,  inasmuch  as  they  supply  physiological 
aids  to  the  psychical  mechanism,  which  alone  in  the  latter 
theories  is  supposed  to  explain  our  separation  of  objects  in 
space. 

(1)  lotze’s  theory 

The  doubtful  contention  of  Lotze  that  the  soul  as  a non- 
spatial  entity  is  only  capable  of  intensive  states  is  reminis- 
cent of  his  spiritualistic  conception  of  the  soul.2  He  places 

1 The  Senses  and  the  Intellect,  2d  ed.,  1864,  pp.  197  ff. 

2 See  p.  30. 


THEORIES  OF  SPATIAL  PERCEPTION 


341 


himself  at  once  beyond  all  the  older  attempts  to  conjure 
spatial  perception  out  of  intensive  states  by  simply  conced- 
ing that  spatial  perception  is  an  original  and  a 'priori  posses- 
sion of  the  soul  which  is  not  produced  by  outer  impressions 
but  merely  turned  by  them  to  special  uses.1  The  perception 
of  the  actual  position  of  outer  objects  is  therefore  not  really 
a perception  or  apperception  but  rather  a re-creation  of 
space.  The  older  attempts  to  find  in  the  sensation  as  such 
characteristics  which  would  force  one  to  a spatial  arrange- 
ment are  inconclusive  for  this  reason  alone,  that  they, 
strictly  speaking,  attempt  to  prove  much  more  than  is  really 
present  in  experience.  For  those  lines  of  thought  are  not 
restricted  to  a certain  field  of  sensation  but  are  valid  for 
sensations  altogether.  Now,  just  as  truly  as  a tone  can 
never  appear  as  a point  of  sensation,  so  can  a color  never 
reach  a purely  spatial  determination. 

Therefore,  with  two  sensations  that  are  going  to  be  sepa- 
rated in  space  there  must  be  combined  auxiliary  determi- 
nants that  will  represent  their  local  character.  This  local 
sign  is  a physical  nervous  process  which  for  each  part  of  the 
nervous  system  has  a constant  association  with  that  varying 
nervous  process  which  supplies  purely  intensive  excitation. 
In  order,  however,  for  the  local  signs  not  only  to  separate 
sensations  spatially  but  also  to  lead  to  a constant  co-ordi- 
nation, they  must  themselves  form  members  of  a regular 
series.  In  the  tactual  sense  they  consist  of  sympathetic 
sensations  that  spread  over  a circle  of  irradiation.  In  the 
formation  of  local  signs  for  the  sense  of  vision  Lotze  for  the 
first  time  uses  to  their  full  extent  the  movements  of  the  eye. 
Each  stimulation  of  the  retina  causes  a reflex  movement 
which  attempts  to  bring  the  stimulus  on  to  the  point  of 
clearest  vision.  After  such  movements  have  been  often 
made  certain  sensations  of  movement  become  associated 
1 Medic.  Psych.,  1852,  II,  chaps.  I and  IV. 


342 


HISTORY  OF  PSYCHOLOGY 


with  each  impression.  Localization  with  the  eye  at  rest 
becomes  possible  owing  to  the  fact  that  in  this  case  the  dif- 
ferent impulses  to  movement  compensate  each  other  and 
call  up  by  means  of  association  the  corresponding  sensations 
of  movement. 

(2)  ITS  PHYSIOLOGICAL  DEVELOPMENT 

The  concept  of  the  local  sign,  the  crucial  point  of  Lotze’s 
theory,  challenged  a closer  investigation  of  its  physiological 
basis.  In  the  tactual  sense  Meissner1  explained  the  physi- 
ological substratum  of  the  hypothetical  circles  of  irradiation 
by  supposing  that  each  stimulus  affects  several  sensitive 
points  in  varying  degrees.  The  hypotheses  of  Czermak2 
made  use  of  a combination  of  Weber’s  circles  of  sensitivity 
and  Lotze’s  local  signs.  His  original  interpretation  of 
Weber’s  experiments  depended  upon  the  manner  in  which 
the  nerve-fibres  spread  out.  Later  on  he  abandoned  these 
anatomical  presuppositions3  and  approached  nearer  to  the 
standpoint  of  Lotze  and  Meissner,  inasmuch  as  he  supposed 
that  each  point  of  the  skin  had  a local  sign  of  the  sensation 
itself  and  also  one  conditioned  by  the  extent  of  the  excita- 
tion. From  these  he  arbitrarily  distinguishes  a third  local 
sign,  one  that  is  immediately  accessible  to  observation, 
namely,  that  of  the  circle  of  sensitivity.  This  last  clearly 
shows  the  inner  contradiction  between  the  theory  of  local 
signs  and  the  theory  of  circles  of  sensitivity. 

The  discovery  of  the  cold,  warm,  and  pressure  spots  of 
the  skin  by  Blix4  in  1882  marked  a decided  advance.  After 
it  had  been  shown  that  with  successive  stimulation  there 
could  be  discrimination  between  two  neighboring  pressure 

1 Beitrdge  zur  Anatomie  u.  Physiologie  d.  Haul , 1852. 

2 Muller's  Archiv,  1849,  p.  252. 

3 Wiener  Sitzungsber.,  Bd.  XV,  1855,  p.  466;  Bd.  XVII,  1855,  p.  577. 

4 Upsala  Lakaref brewings  fork.,  Bd.  XVIII,  1882-3. 


THEORIES  OF  SPATIAL  PERCEPTION 


343 


spots  the  theory  of  circles  of  sensitivity  had  to  be  finally 
abandoned.1 

(3)  ITS  PSYCHOLOGICAL  DEVELOPMENT 

The  motive  for  a deeper  psychological  interpretation  of 
the  theory  of  local  signs  lay  in  the  fact  that  it  really  remained 
unexplained  how  purely  qualitative  characteristics  found  in 
sensations  because  of  a special  nervous  process  could  lead 
to  an  extensive  or  spatial  differentiation.  In  this  sense 
Wundt2  was  the  first  to  investigate  the  psychological  sig- 
nificance of  local  signs.  Each  point  of  the  surface  of  our 
skin  contributes  to  the  sensation  a definite  local  character- 
istic which,  because  of  experience,  is  differentiated  from  the 
different  qualities  of  the  impressions.  This  special  quality 
of  a sensation,  as  soon  as  it  appears  as  a partial  content  of  a 
perception,  arouses  a visual  image  of  the  place  corresponding 
to  it.  For  one  born  blind  the  muscle  sensations  caused  by 
touching  objects  form  a similar  means  of  assistance. 

In  a similar  manner  visual  percepts  are  interpreted  as  a 
common  product  of  retinal  image  and  kinaesthetic  image. 
From  the  empirical  fact  that  in  percepts  of  the  perfected 
visual  sense  sensation  qualities  of  the  retina  and  kinaesthetic 
sensations  of  the  eyeball  are  known  to  be  at  work  we  can 
draw  the  conclusion  that  both  factors  have  contributed  to 
the  origin  of  visual  percepts.3  With  the  original  qualitative 
differences  of  the  retinal  sensations  which  are  dependent 
upon  the  place  of  stimulation  there  are  combined  the  dif- 
ferent degrees  of  intensity  of  the  sensations  of  strain  ac- 
companying movements  and  positions  of  the  eye.  All 
localization  is  therefore  dependent  upon  a system  of  com- 

1 Cf.  M.  von  Frey  and  R.  Metzner,  Zeitschr.  /.  Psychol.,  Bd.  XXIX, 
1902,  pp.  161  ff. 

2 Beitrage  zur  Theorie  der  Sinneswahrnehmung,  1862. 

3 “ tJber  das  Sehen  mit  einem  Auge,”  op.  cit.,  pp.  105  jf. 


344 


HISTORY  OF  PSYCHOLOGY 


plex  local  signs.  A closer  insight  into  the  process  of  the 
formation  of  ideas  proves  the  latter  to  be  a kind  of  assimila- 
tive fusion.  Now,  since  each  position  of  the  eye  has  cor- 
responding to  it  a complex  of  pressure  sensations  in  the 
eyeball  and  of  local  signs  of  the  retina,  the  fusion  products 
form  a qualitative  local  sign  system  of  two  dimensions. 
This  system  controls  the  flat  visual  field  of  monocular 
vision,  and  in  binocular  vision  a local  sign  system  of  the 
second  order  is  added,  the  members  of  which  are  the  local 
signs  for  depth.1 

The  concept  of  the  local  sign  has  been  retained  in  all  later 
genetic  theories.  It  has,  however,  occasionally  relapsed  into 
its  simple  primitive  meaning;  i.  e.,  as  depending  no  longer 
upon  movement  reflexes  as  with  Lotze  but  upon  purely 
qualitative  differences  in  sensation,  which  also  occur  with 
the  eye  at  rest.  From  this  point  of  view  T.  Lipps2  formu- 
lated a theory  of  visual  space  presupposing  that  sensations 
on  different  points  of  the  retina  are  somehow  different  and 
become  bound  to  each  other  or  opposed  to  each  other  ac- 
cording as  they  are  near  to  or  far  from  each  other.  These 
arrangements,  innate  in  the  individual,  arise  in  the  species 
from  the  fact  that  impressions  from  different  retinal  points 
more  often  correspond  the  nearer  they  are.  Now,  similar- 
ity of  impressions  occasions  their  fusion,  dissimilarity  their 
separation.  The  same  thing  is  true  for  the  sense  of  touch. 
Whereas  with  Wundt  the  local  signs  of  the  skin  achieved  a 
spatial  significance  only  through  the  mediation  of  another 
sense,  Lipps,  on  the  other  hand,  thought  he  could  explain 
separation  in  space  by  means  of  sensation  signs  differing 
merely  in  quality,  with  this  proviso,  however,  that  the  tactual 
image  in  general  corresponds  to  the  spatial  arrangement  of 
the  stimulated  points.  Different  points  of  the  skin  will  be 

1 W.  Wundt,  Grundz.  d.  physiol.  Psychol.,  II,  6th  ed.,  1910,  pp.  716  jj. 

2 Grundtatsachen  d.  Seclenlebens,  1883,  pp.  515  ff. 


THEORIES  OF  SPATIAL  PERCEPTION 


345 


the  more  often  simultaneously  stimulated  the  nearer  to  each 
other  they  are  and,  conversely,  more  seldom  the  farther 
apart  from  each  other  they  lie.  Simultaneous  stimulation 
gives  rise  to  a tendency  to  fuse,  non-simultaneous  to  a ten- 
dency to  separate  the  impressions.  Lipps  regards  this  ten- 
dency as  valid  not  only  for  stimuli  of  the  same  sense,  but 
as  a law  of  the  spatial  complication  for  disparate  stimuli  it 
becomes  also  a secondary  principle  which  binds  together 
the  independent  spatial  percepts  of  the  sense  of  vision  with 
those  of  the  sense  of  touch. 


CHAPTER  XII 


THEORIES  OF  FEELING  AND  VOLITION 

In  the  history  of  psychological  thought  we  can  separate 
easily  two  chief  lines  along  which  theoretical  opinions  as  to 
the  subjective  side  of  the  conscious  life  have  moved,  namely, 
theories  of  feeling  and  theories  of  volition.  We  shall  limit 
ourselves  to  these  elementary  phenomena.  The  opinions 
about  the  higher  processes  of  consciousness  are  partly  de- 
pendent upon  these  and  partly  show  themselves  in  the 
hypotheses  which  have  been  treated  in  discussing  the 
general  trend  of  psychological  thought  (Chapters  I-III). 

i.  Theories  of  Feeling 

Characteristic  phenomenological  presuppositions  serve  as 
preliminaries  to  the  several  theories.  The  differences  among 
these  influence  in  a peculiar  manner  the  attempts  at  a theo- 
retical explanation.  Theories  of  feeling  can  in  general 
be  differentiated  according  to  the  relation  in  which  the 
affective  experiences  are  supposed  to  stand  to  the  other 
contents  of  consciousness.  At  first  feelings  were  considered 
as  modifications  of  another  psychical  activity,  and  thereby 
the  primitive  need  for  unification  was  most  easily  satisfied. 
Corresponding  to  the  intellectualism  of  all  beginnings  of 
psychological  thought,  cognition  or,  in  general,  ideational 
activity  takes  the  place  of  a supraordinated  function.  Then 
there  appear  theories  which  indeed  recognize  the  psycho- 
logical peculiarities  of  the  feelings  but  try  to  deduce  them 
from  other  foreign  conditions.  These  attempts  in  part  try 

346 


THEORIES  OF  FEELING  AND  VOLITION 


347 


to  deduce  them  from  other  psychical  contents,  such  as  ideas 
and  their  interrelations,  and  so  lead  to  psychomechanic 
theories  of  feelings  and  again  bring  forward  physiological 
connecting-links,  admitting  heterogeneity  between  feelings 
and  the  intellectual  contents  of  consciousness.  In  contra- 
distinction to  all  these  there  stands  the  group  of  theories 
which  preserves  the  psychological  nature  of  feelings  and,  as 
with  other  processes  of  consciousness,  attempts  to  explain 
them  as  psychophysical  processes. 

(a)  Phenomenological  Presuppositions 

The  best  orientation  for  theories  of  feelings  can  be  obtained 
from  the  classification  of  the  contents  of  consciousness.1 
The  dependent  position  of  the  feelings  contrasts  plainly  with 
that  of  the  sensations  and  sense-perceptions,  which  from  the 
very  beginning  secured  a sure  place  in  psychological  classifi- 
cations. On  the  other  hand,  the  feelings  have  wandered 
restlessly  from  one  group  of  the  contents  of  consciousness  to 
another.  As  often  as  the  phenomenological  presuppositions 
changed,  the  attempts  to  explain  the  nature  of  the  feelings 
changed  also. 

The  alternative  reaching  furthest  back  is  the  one  that 
asks  the  question  whether  feelings  are,  like  ideas,  psychical 
acts  that  refer  to  a special  object  or  whether  they  refer  only 
to  the  ways  in  which  the  other  real  acts  of  perception  and 
ideation  come  to  consciousness. 

In  spite  of  all  other  differences  in  the  question  of  feelings, 
the  second  of  the  two  possibilities  has  almost  unanimously 
been  accepted.  From  Aristotle  onward  descriptions  of  feel- 
ings have  generally  taken  this  direction.  It  is,  however, 
only  in  connection  with  his  Ethics 2 that  he  speaks  of  plea- 
sure as  connected  with  certain  psychical  activities,  and  as 

1 Cf.  p.  190,  above.  2 Ethic.  Nic.,  X,  chs.  IV  and  V. 


348 


HISTORY  OF  PSYCHOLOGY 


completion  of  the  act  it  may  change  in  accordance  with  the 
kind  of  act.  The  later  English  psychologists  agreed  with 
James  Mill1  in  teaching  that  the  feeling  accompanying  the 
perception  is  contained  in  the  act  itself.  And  Bain  went  so 
far  in  his  description  of  the  relation  of  feeling  to  sense-per- 
ception as  to  maintain  that  each  sensation  has  a double 
characteristic,  an  intellectual  and  an  emotional  side. 

In  German  psychology  Domrich2  called  feeling  the  way 
in  which  consciousness  was  excited  by  perception.  This  ex- 
planation has  been  retained  by  many  even  to  the  present 
day.  Nahlowsky3  differentiated  feeling  proper  from  the 
pleasure  and  pain  immediately  connected  with  sensation, 
i.  e.,  the  so-called  feeling  tone.  This  was  taken  up  by  the 
Herbartians  Waitz  and  Volkmann,  since  it  gave  them  the 
possibility  of  saving  the  Herbartian  theory  from  the  notion 
that  all  feelings  arose  from  some  relation  between  ideas. 

There  is  less  consensus  of  opinion  in  deciding  the  opposite 
question  whether  every  psychical  act  must  be  necessarily 
accompanied  by  a feeling.  This  problem  really  belongs  to 
modern  psychology,  inasmuch  as  it  discovered  the  contra- 
dictions in  the  traditional  theories.  We  do,  however,  find 
that  Aristotle  in  his  Ethics'1  says  that  not  only  all  kinds 
of  sensations  but  also  all  psychical  activities  are  accom- 
panied by  feelings,  although  in  his  psychology5  he  speaks  of 
indifferent  sensations,  i.  e.,  without  feelings.  In  the  nine- 
teenth century  we  find  both  points  of  view.  James  Mill6 
emphatically  upholds  indifferent  sensations.  Just  as  em- 
phatically do  A.  Bain  and  J.  S.  Mill  maintain  that  each 
sensation  has  an  accompanying  feeling.  These  latter  are 
joined  by  so  many  psychologists  that  Horwicz  takes  it  as 

1 Anal,  of  the  Phen.  of  the  Hum.  Mind,  II,  ch.  XVII. 

2 Die  psychischen  Zustande,  ihre  organische  Vermittlung  und  ihre 
Wirkung  in  Erzeugung  korperlicher  Krankheiten,  1849. 

3 Das  Gefiihlsleben,  1862,  Einleitung.  1 Ethic.  Nic.,  X,  ch.  IV. 

3 De  An.,  Ill,  7.  6 Op.  cit.,  II,  ch.  XVII. 


THEORIES  OF  FEELING  AND  VOLITION 


349 


an  almost  universally  recognized  fact  that  all  sensations  are 
accompanied  by  differing  degrees  of  pleasantness  and  un- 
pleasantness. 

Lastly,  it  would  seem  as  if  these  two  diametrically  op- 
posed view-points  could  be  brought  into  unison.  The 
Wundtian  theory  of  feeling  acknowledged  indifferent  psy- 
chological processes  in  spite  of  the  fact  that  feelings  in 
general  were  defined  as  reactions  of  apperception  to  the 
separate  contents  of  consciousness.  Each  sensation  of  a 
moderate  intensity  is  accompanied  by  a feeling  of  pleasure, 
of  a greater  intensity  by  a feeling  of  displeasure.  Since, 
however,  the  feeling  character  changes  constantly  with  the 
intensity  of  the  sensation,  an  indifference  point  must  lie 
somewhere  between  the  two  opposites.  Against  this  theory 
Brentano1  has  urged  the  following  objection,  that  the  dis- 
pleasure arising  with  a great  intensity  of  sensation  is  not 
really  connected  with  the  quality  of  the  sensation  but  rather 
with  the  sensation  of  pain  accompanying  the  increased  in- 
tensity of  the  sensation. 

The  most  convincing  proof,  however,  of  the  ambiguity  of 
the  phenomena  in  question  is  the  dispute  as  to  whether  feel- 
ings can  be  arranged  in  one  or  more  than  one  dimension. 
The  pleasure-pain  theory,  which  arranges  all  feelings  be- 
tween these  two  opposites,  has  from  the  very  beginning 
been  favored  by  ethical  and  aesthetic  motives.  In  principle 
it  is  still  held  by  many  prominent  psychologists  of  the  pres- 
ent day,  e.  g.,  Jodi  and  Kiilpe.  By  others  it  is  just  as 
emphatically  rejected  as  insufficient  on  introspective  evi- 
dence. Above  all,  Wundt2  showed  its  insufficiency  for  the 
description  of  the  effects  of  colors  and  clangs.  T.  Lipps3 
also  expressed  his  conviction  that  there  exists  a number 
of  elementary  feelings.  The  most  modern  revision  of  this 

1 Op.  tit.,  pp.  197  ff. 

2Grundzuge  d.  phys.  Psych.,  1st  ed.,  1874,  pp.  436  ff. 

3 Selbstbewusstsein,  Empfindung  und  Gefuhl,  1901. 


350 


HISTORY  OF  PSYCHOLOGY 


question  stands  in  close  connection  with  the  postulation  of 
new  classes  of  states  of  consciousness,  as  in  the  so-called 
states  of  awareness.1  The  definite  acceptance  and  the  pos- 
sible range  of  these  new  concepts  seem  to  many  psy- 
chologists to  be  necessary  factors  in  the  ultimate  decision 
as  to  the  place  of  the  feelings. 

( b ) Intellectualistic  Theories  of  Feeling 

Under  the  protection  of  intellect ualism,  theories  of  this 
kind,  although  really  at  the  uttermost  limit  of  proper 
psychological  analysis,  can  be  traced  through  the  whole 
history  of  psychology.  The  Aristotelian  comparison  of 
pleasure  with  assent  and  pain  with  negation  contains  the 
elements  of  a theory  which  recognizes  feeling  as  a mode  of 
the  activity  of  cognition.  His  theory  of  the  emotions  falls 
under  the  same  point  of  view,  for  it  is  intimately  associated 
with  ethical  considerations.  Aristotle’s  famous  description 
of  the  emotions,  with  its  ethically  significant  differentiation 
between  the  emotions  and  the  passions,  has  been  a model 
for  centuries.  He  crowned  his  ethics  with  the  statement 
that  the  highest  pleasure  is  occasioned  by  the  activity  of 
the  highest  faculty  of  the  soul,  the  i 'o5?,  The  experience 
of  the  valuable,  which  theoretical  knowledge  brings,  spreads 
to  other  experiences.  This  theory  shows  only  a few  new 
points  of  view  during  succeeding  ages.  Spinoza  went  to 
the  support  of  the  old  differentiation  between  activity  and 
passion  with  all  the  means  furnished  by  the  more  modern 
theory  of  knowledge.  The  affection  is  an  activity  or  pas- 
sion according  to  the  clearness  or  unclearness  of  the  mo- 
tivating idea.  Locke2  was  content  with  the  neutral  desig- 
nation of  pleasure  and  pain  as  simple  ideas  which  are 
related  to  different  states  of  the  soul. 

1 See  pp.  136  and  211.  2 Human  Understanding,  II,  ch.  XI. 


THEORIES  OF  FEELING  AND  VOLITION 


351 


The  association  psychology  gave  impetus  to  new  view- 
points. Hume  considered  the  feelings  as  impressions  of 
self-perception  by  means  of  the  ideas  and  brought  about  a 
connection  between  these  two  by  means  of  association.  On 
the  other  hand,  the  attempt  was  made  to  explain  how  it 
was  and  in  what  way  the  affective  experiences  could  arise 
out  of  a special  kind  of  cognition.  With  such  an  intention 
Leibniz1  brought  the  feelings  into  connection  with  confused 
or  unclear  ideas.  He  was  joined  in  the  nineteenth  century 
by  Hegel  with  his  well-known  explanation  of  the  feelings  as 
an  obscure  kind  of  knowledge.  Contradicting  his  master 
on  this  point,  Ch.  Wolff  described  feeling  precisely  as  an 
intuitive  knowledge  of  the  state  of  the  body  and  pleasure 
or  pain  as  arising  according  to  the  perfection  or  imperfec- 
tion of  this  knowledge.  The  concept  of  perfection,  the 
ethical  and  aesthetic  ideal  of  the  eighteenth  century,  thus 
became  dominant  in  the  theory  of  feelings  as  well.2  Echoes 
of  the  old  ways  of  thinking  are  still  heard  in  the  post-Kant- 
ian  psychology,  although  the  recognition  of  feelings  as  a 
special  class  of  psychical  processes  was  hardly  denied  after 
Kant.  Such  trains  of  thought  were  apt  to  arise  in  the  in- 
terpretation of  the  so-called  common  or  organic  feelings, 
which  seemed  to  give  direct  information  as  to  the  well-being 
of  the  body.  Some  interpreted  the  organic  feelings  as  a 
consciousness  of  the  state  of  health  of  the  body,3  others 
described  them  as  a struggle  of  the  weaker  sensations  from 
different  organs  of  the  body  trying  to  rise  into  conscious- 
ness.4 At  this  point  the  intellectual  theory  of  feelings  goes 
over  into  a sensational  theory.5 

1 Nouveaux  Essays,  II,  ch.  XX,  § 6. 

2 For  the  relation  of  psychology  and  aesthetics,  cf.  R.  Sommer, 
Grundzuge  einer  Geschichte  der  deutschen  Psychologie  und  Asthetik  von 
Wolff-Baumgarten  bis  Kant-S chiller,  1892. 

3 George,  Die  funf  Sinne,  1846,  pp.  44  ff. 

4 Waitz,  Grundlegung  d.  Psych.,  1846,  p.  64.  6 Cf.  p.  355. 


352 


HISTORY  OF  PSYCHOLOGY 


(c)  Psychomechanical  Theories  of  Feeling 

The  theory  that  all  feelings  depend  upon  the  reciprocal 
action  of  ideas  goes  back  to  the  observation  that  several 
aesthetic  feelings  are  dependent  upon  the  relations  of  simple 
impressions.  The  earliest  to  be  recognized  were  the  feel- 
ings arising  from  musical  intervals  in  regard  to  their  depen- 
dence upon  the  relations  of  tone  sensations.  We  have  the 
old  story  of  Pythagoras  in  the  blacksmith’s  shop  hearing 
different  consonant  intervals  in  the  clang  of  the  hammers. 
In  the  weight  of  the  different  hammers  he  traced  the  rela- 
tions of  the  fifth,  the  fourth,  etc.  In  the  field  of  aesthetics 
this  correlation  of  the  feelings  with  the  relations  between 
ideas  was  pursued  further.  Aristotle  tried  to  put  upon  a 
sure  foundation  the  Platonic  specifications  of  the  beautiful 
by  adding  a series  of  psychological  characteristics.1  Unity, 
inner  connection,  the  golden  mean  between  extremes,  simi- 
larity of  parts  or  their  relations  characterize  the  aestheti- 
cally valuable.  The  corresponding  relations  between  ideas 
form  the  subjective  correlates  of  these  objective  facts. 

These  purely  psychological  beginnings  of  a theory  of  feel- 
ings based  upon  the  relations  of  ideas  to  each  other  soon 
received  support  from  the  presuppositions  of  materialistic 
psychology.  According  to  this  latter  the  real  harmony  or 
the  conflict  of  the  bodily  processes  that  underlie  all  ideational 
activity  is  the  decisive  factor  for  pleasure  or  pain.  The 
older  interpretations  of  this  kind  did  not  start  with  the 
simple  feelings  but  rather  with  the  more  intense  affections, 
such  as  the  emotions.  In  ancient  times  Zeno  the  Stoic 
gave  the  famous  definition  of  an  emotion  as  a movement  in 
opposition  to  the  nature  of  the  soul,  which  we  can  picture 

1 Cf.  0.  Kulpe  in  Philos.  Abh.,  M.  Heinze  zum  70.  Geburtstage,  1906,  pp. 
101  ff. 


THEORIES  OF  FEELING  AND  VOLITION 


353 


concretely  as  a twisting  of  the  soul  pneuma.  In  modern 
psychology  the  same  standpoint  is  seen  in  Descartes’  theory 
of  the  emotions.1  Its  definition  of  the  emotions  as  excita- 
tions of  the  soul  due  to  the  movement  of  the  animal  spirits 
upholds  the  old  opinion  that  the  emotions,  as  affections  of 
the  soul,  require  a physical  basis.  The  more  such  attempts 
keep  to  the  lines  of  thought  of  materialistic  psychology  the 
more  do  they  depart  from  a real  theory  of  feeling. 

On  the  dividing  line  between  metaphysical  myths  and 
empirical  theories  there  stands  in  the  eighteenth  century 
the  theory  of  C.  Bonnet.  He  is  to  be  credited  with  the  em- 
pirical differentiation  between  feeling  and  sensation,  as  we 
should  say  in  our  modern  terminology.  In  the  impression 
which  an  object  produces  we  must  differentiate  that  which 
characterizes  the  object  from  that  which  determines  the 
reaction  of  the  soul.  The  latter  is  the  feeling  which  ap- 
pears in  two  chief  kinds,  as  pleasure  and  pain.  The  real 
cause  of  pleasure  is  supposed  to  be  due  to  a moderate  ex- 
citation of  the  fibres  of  the  brain.  Besides  this  there  is  a 
relative  pleasure  arising  from  the  excitation  of  different 
kinds  of  fibres;  in  this  class  belongs  the  harmonious  effect 
of  combinations  of  certain  tones  or  colors  which  arise  out  of 
a certain  succession  or  combination  of  movements  in  the 
sensory  fibres.  It  was  Herbart,  however,  who  finally  and 
decisively  separated  the  psychological  part  of  these  theories 
from  their  materialistic  presuppositions  and  thereby  for- 
mulated a purely  psychomechanical  theory  of  feeling. 
Herbart’s  theory  was  also  not  without  forerunners.  We 
can  trace  it  back  to  Scholasticism,  and  find  Buridan2  making 
the  peculiar  attempt  to  describe  the  feelings  from  the  stand- 
point of  a psychical  mechanism,  certainly  a very  primitive 
one.  The  soul  strives  to  prolong  a pleasant  experience  and 

1 De  pass,  an.,  I,  27. 

2 Ethic.,  VII,  25/.,  202  a;  26/.,  203  a (ed.  1489). 


HISTORY  OF  PSYCHOLOGY 


354 

! 

to  terminate  an  unpleasant  one;  as  long  as  it  is  occupied 
by  one  single  feeling  it  cannot  bring  another  into  conscious- 
ness to  the  same  degree.  If  feelings  of  the  same  kind  occur 
simultaneously,  they  serve  mutually  to  strengthen  each 
other,  just  as  pleasure  at  the  sight  of  a flower  is  increased 
by  the  pleasure  arising  from  its  scent.  Opposite  feelings, 
on  the  other  hand,  tend  to  weaken  each  other.1 

These  influences  were  certainly  not  without  effect  during 
the  following  centuries.  The  most  decisive  thing  in  Her- 
bart’s  theory  was  the  surprising  combination  of  a psychical 
mechanism  with  an  extreme  intellectualism.  For  Herbart 
feelings  are  ideas  which  oppose  or  hinder  each  other.  The 
state  of  ideation  itself  is  a strain,  since  ideation  as  an  activ- 
ity strives  to  maintain  itself  and  is  nevertheless  continually 
subjected  to  inhibition.  In  particular,  feelings  are  differen- 
tiated into  those  that  are  determined  by  the  content  to 
which  they  refer  and  those  that  are  dependent  upon  the 
general  affective-conative  state.  To  the  first  group  belong 
the  sesthetic  and  sense  feelings,  both  of  which  are  made  up 
of  partial  ideas;  to  the  second  group  belong  the  emotions. 

The  most  important  change  that  the  Herbartian  school 
made  in  the  theory  of  feelings  handed  down  to  them  by 
their  master  consisted  in  the  separation  of  sense-feelings  as 
“the  tone  of  a sensation”  from  feelings  proper.2  They 
candidly  admitted  that  difference  in  experiences  which 
Herbart  had  only  with  difficulty  been  able  to  overcome  by 
means  of  his  artificial  theory  of  partial  ideas.  The  question 
as  to  the  tone  of  sensations  has  remained  a matter  of  dis- 
pute down  to  the  present  time.  In  recent  times  af- 
fective sensations  are  spoken  of  and  they  are  supposed  to 
belong  to  the  class  of  sensations.3  This  is,  of  course,  purely 

1 Cf.  P.  91. 

2 Cf.,  e.  g.,  Volkmann,  Lehrb.  d.  Psychol.,  1875,  p.  236. 

3 See  p.  206. 


THEORIES  OF  FEELING  AND  VOLITION 


355 


a question  of  classification  and  has  directly  nothing  to  do 
with  definite  theories  of  feeling.  If,  however,  such  am- 
biguity reigns  in  mere  descriptions  of  our  affective  experi- 
ences, then  the  attempts  at  theoretical  interpretation  are 
very  likely  to  diverge  to  a much  greater  degree. 

(d)  Physiological  Theories  of  Feeling 

Attempts  to  build  up  a theory  of  feelings  on  physiological 
characteristics  lead  first  of  all  to  the  hypothesis  that  feel- 
ings have  as  their  substratum  nerve  processes  which  are 
similar  to  those  that  condition  the  rise  of  a sensation.  Under 
the  influence  of  modern  brain  physiology  this  opinion  soon 
merged  into  the  theory  that  it  was  a question  of  central 
nervous  processes. 

Because  of  their  psychological  presuppositions  and  con- 
clusions the  hypotheses  of  the  first  kind  represent  sensa- 
tional hypotheses  of  feeling.  Feelings  are  classified  as  a 
special  quality  of  sensation  along  with  the  other  sensations, 
from  which  they  are  differentiated  only  by  the  fact  that  they 
can,  in  their  capacity  as  a general  sensation,  accompany  any 
other  sensation.  The  nerves  of  the  skin  and  of  the  inner 
organs  that  have  to  do  with  organic  sensations  are  sup- 
posed to  be  the  bearers  of  that  special  sensation  quality. 
This  point  of  view  was  upheld  about  the  middle  of  the  nine- 
teenth century  by  Domrich1  and  Hagen2,  and  it  found  a 
welcome  support  because  of  the  customary  confusion  be- 
tween the  concepts  of  sensation  and  feeling. 

Besides  this  the  older  opinions  common  among  physiol- 
ogists as  to  the  nature  of  the  organic  feelings  seem  to  have 
influenced  psychology.  In  physiology,  from  time  immemo- 
rial, organic  feeling  (ccenaesthesis)  has  been  contrasted  with 

1 Die  psychischen  Zustande,  1849. 

2 Psychologische  Untersuchungen,  1842. 


356 


HISTORY  OF  PSYCHOLOGY 


the  sensations  of  the  outer  senses  as  an  apprehension  of 
the  state  of  the  inner  organs,  and  this  was  brought  about 
by  the  sensory  nerves  of  those  organs.  This  unsatisfactory 
distinction  was  abandoned  by  J.  Muller  from  psychological 
motives.  Because  of  the  similarity  of  those  sensations 
classed  together  as  organic  sensations  with  those  of  the 
tactual  or  “feeling”  sense,  he  put  them  all  into  the  same 
group.  E.  H.  Weber  went  a step  further,  inasmuch  as  he 
presupposed  a double  method  of  sensation  of  those  parts 
supplied  with  sensory  nerves,  namely,  sensations  proper  and 
organic  feelings,  which  latter  give  us  a consciousness  of  our 
bodily  condition.  In  order  to  round  this  out  to  a general 
theory  of  feeling  it  was  only  necessary  to  extend  this  same 
thought  to  all  feelings.  This  was  done  by  Lotze1  when  he 
sacrificed  his  older  intellectualistic  conception  of  feeling  as 
an  unconscious  judgment  of  the  harmony  or  lack  of  har- 
mony among  the  vital  functions  of  the  body2  and  consid- 
ered feeling  to  arise  by  means  of  a specific  nerve  process 
that  changes  with  the  intensity  and  quality  of  the  sensory 
stimulation. 

An  important  set  of  facts  had  up  till  now  been  insufficiently 
noticed  in  the  majority  of  these  theories,  i.  e.,  the  relation 
of  feelings  to  the  movements  of  expression.  From  the  stand- 
point of  the  physiological  theories  these  could  be  explained 
by  the  co-operation  of  the  central  physiological  processes. 
The  feelings  themselves  were  then,  following  the  explana- 
tion of  Ribot,3  generally  transformed  into  phenomena  of  the 
central  nervous  system  accompanying  the  bodily  processes. 
They  were,  however,  at  the  same  time  supposed  to  express 
the  general  state  of  the  body.  This  is  Meynert’s4  view,  who 
explained  the  feeling  of  joy  as  due  to  functional  hyper- 

1 Medic.  Psychol.,  p.  233. 

2 See  article,  “Seele,”  in  Wagner’s  Handworterbuch,  Bd.  Ill,  1,  p.  191. 

3 La  psychologic  des  sentiments,  1897. 

4 Klinische  Voerlsungen  uber  Psychiatric,  1897. 


THEORIES  OF  FEELING  AND  VOLITION 


357 


semia  of  the  brain,  whereas  anaemia  caused  by  the  contrac- 
tion of  the  arteries  gives  rise  to  sadness.  The  most  influ- 
ential of  the  varieties  of  this  theory  has  been  the  one 
that  has  emphatically  degraded  feelings  to  mere  secondary 
states.  According  to  James  and  Lange,  a stimulus  calls 
forth  as  a reflex  the  movement  of  expression.  The  sensa- 
tions arising  from  this  movement  are  then  the  real  basis  for 
our  affective  experiences.  As  James’s  oft-quoted  sentence 
has  it:  “We  do  not  weep  because  we  are  sad,  but  we  are 
sad  because  we  weep.”1  With  Lange2  this  view  is  extended 
to  a general  relationship  between  physical  and  psychical 
states — a relationship  that  can  be  criticised  from  the  stand- 
point of  theory  of  knowledge.  As  long  as  we  consider  the 
psychical  state  as  the  cause  and  the  physical  state  as 
the  effect,  it  remains  incomprehensible  why  it  should  give 
rise  to  these  special  physical  symptoms.  If,  however,  we 
reverse  this  relationship  the  state  of  the  soul  becomes  readily 
comprehensible  since  it  is  simply  the  sensation  of  all  bodily 
disturbances.  This  theory  found  favorable  ground  in  the 
discussion  of  the  emotions.  Lange  described  these  as  sen- 
sations of  organic  disturbances  produced  by  the  changes  in 
innervation  of  the  sympathetic  nerves.  In  support  of  his 
theory  he  pointed  to  the  great  extent  of  the  movements  of 
expression  and  to  the  reinforcing  reaction  they  have  upon 
the  emotions.3  The  fundamental  truth  in  this  theory,  which 
is  seen  in  the  facts  of  sympathetic  movements  and  in  the 
peripheral  irradiation  of  the  motor  excitation  accompany- 
ing every  feeling,  has  gained  for  it  much  sympathy. 

1 Mind,  O.  S.  IX,  1884,  pp.  189  /. 

2 Uber  Gemutsbewegungen,  1887. 

3 For  some  anticipations  of  this  theory,  see  Titchener,  A Text-Book 
of  Psychology,  II,  1910,  p.  479. 


358 


HISTORY  OF  PSYCHOLOGY 


(e)  Psychophysical  Theories  of  Feeling 

With  the  recognition  of  feelings  as  independent  kinds  of 
contents  of  consciousness  the  problem  of  psychophysical 
theories  of  feeling  becomes  slightly  different  from  what  it 
formerly  was.  It  is  no  longer  a question  of  a dissolution 
of  feeling  into  the  other  contents  of  consciousness  but  rather 
a psychophysical  interpretation  of  the  affective  processes. 
This  can,  of  course,  lead  to  quite  different  results  accord- 
ing to  differences  in  collateral  points  of  view.  The  recog- 
nition of  feelings  as  belonging  to  the  general  classes  of 
psychical  processes  was  the  first  step  toward  theories  of 
this  kind.  But  the  interpretation  of  feelings  as  states  into 
which  the  soul  is  placed  by  means  of  its  sensations  and  ideas 
allowed,  on  the  one  hand,  the  thought  to  arise  that  the  feel- 
ing contains  within  itself  a dim  knowledge  of  the  real  state 
of  the  soul,  and  by  allowing  this  the  theory  at  once  became 
an  intellectualistic  one.  And,  on  the  other  hand,  this  in- 
terpretation, by  its  presupposition  of  a metaphysical  con- 
cept of  the  soul,  went  far  beyond  the  immediate  knowledge 
derived  from  self-observation.  It  remained  for  the  psychol- 
ogy of  the  nineteenth  century  to  get  rid  of  those  intellec- 
tualistic and  metaphysical  motives.  Since  the  time  Wundt1 
emphasized  feeling  as  that  side  of  self-consciousness  which 
relates  to  the  real  state  of  the  perceiving  subject,  there  was 
started  a more  exact  analysis  which  ultimately  made  this 
relation  to  self-consciousness  untenable.  For,  in  contra- 
distinction to  self-consciousness,  which  is  a much  later 
development,  feeling  represents  an  original  content  of  con- 
sciousness. The  direction  in  which  Wundt  himself  later 
interpreted  the  feelings  as  psychophysical  processes  was 
determined  for  him  by  the  supposition  of  a very  close  con- 
1 Vorles.  ub.  d.  Menschen-  u.  Tierseele,  1863. 


THEORIES  OF  FEELING  AND  VOLITION 


359 


nection  between  the  great  variety  of  affective  states  and  the 
physiological  symptoms  of  expression.1 

Of  the  theories  that  fall  within  the  group  we  are  discussing 
there  remains  to  be  mentioned  the  one  that  departs  furthest 
from  the  immediate  experience  of  consciousness,  inasmuch 
as  it  sees  in  the  affective  states  the  evolutional  starting- 
point  for  all  kinds  of  contents  of  consciousness.  A.  Hor- 
wicz  in  this  sense  regarded  feelings  as  the  most  original  in- 
dependent psychical  states,  out  of  which  sensations  and 
ideas  had  developed.2  His  theory  has  lasted  in  some  form 
or  other  down  to  the  present  time  because  of  the  favor 
with  which  any  line  of  thought  connected  with  evolution 
is  regarded.  We  meet  it  also  in  some  American  text-books 
of  psychology  in  which  at  times  a cautious  adherence  to 
experience  is  combined  with  the  most  audacious  biogenetic 
hypotheses.3 


2.  Theories  of  Volition 

Whereas  the  feelings,  in  spite  of  their  ceaseless  change,  can 
easily  be  grasped  as  unitary  processes  the  characteristics  of 
which  are  independent  of  the  flow  of  time,  volitional  experi- 
ences, on  the  other  hand,  group  themselves  so  character- 
istically into  different  stages  that  the  separate  theories  of 
volition  can  be  differentiated  according  to  the  stage  in  the 
course  of  the  volitional  process  that  they  have  chosen  as 
their  starting-point.  In  doing  this  the  will  has  traversed 
the  whole  ladder  of  psychical  functions  from  an  absolutely 
transcendental  faculty  down  to  the  idea  accompanying  a 
reflex  movement.  And  the  analysis  has  met  with  greater 
difficulties  the  more  the  problems  of  ethics  have  been  al- 
lowed to  come  to  the  front.  In  this  confusion  with  purely 

1 Cf.  Grundz.  d.  phys.  Psych.,  II,  6th  ed.,  pp.  368  jj. 

- Psychologische  Analysen,  Bd.  II,  1878. 

3 Cf.,  e.  g.,  E.  B.  Titchener,  A Text-Book  of  Psychology,  I,  1909,  § 74. 


360 


HISTORY  OF  PSYCHOLOGY 


philosophical  questions  the  history  of  volitional  theories 
shows  clearly  again  that  change  in  view-point  that  has  de- 
termined the  fate  of  so  many  psychological  theories. 

The  theory  of  volition  was  naturally  influenced  by  the 
original  intellectualism  of  all  psychological  theories.  Ob- 
viously, here  has  been  chosen  as  a starting-point  that  stage 
in  the  developed  volitional  act  that  seems  to  be  experienced 
as  a choice  between  possibilities  and  which  seems  to  show 
most  clearly  its  dependence  upon  intellectual  processes.  In 
contradistinction  to  these  intellectualistic  theories  we  have 
the  absolute  ones  which,  emphasizing  the  experience  of 
decision  or  resolution,  regard  the  will  as  a transcendental 
power  or  faculty.  Common  to  both  these  volitional  theories 
is  the  fact  that  they  are  nourished  by  the  ethical  problem  of 
the  freedom  of  the  will.  Among  the  theories  that  consider 
the  psychological  constitution  of  volitional  experiences  we 
have,  first  of  all,  a group  of  heterogenetic  theories  which 
attempt  to  deduce  the  will  from  other  psychical  processes. 
When  more  emphasis  is  laid  upon  the  feelings  that  accom- 
pany every  act  of  will  we  are  led  gradually  from  the  latter 
theories  to  the  emotional  theories  of  volition. 

Even  though  all  these  theories  of  volition  have  to  do  with 
the  same  problem,  yet  we  are  scarcely  justified  in  judging 
the  older  theories  by  the  same  standards  by  which  we 
judge  the  modern  theories.  For  modern  psychology  has 
found  in  the  reaction  experiment  a help  toward  an  extraor- 
dinarily refined  quantitative  and  qualitative  analysis.1 
The  old  struggle  about  the  problem  of  the  freedom  of  the 
will  is  entirely  different  from  the  careful  description  of  simple 
volitional  processes  which  modern  psychology  attempts  to 
give. 

1 Cf.,  e.  g.,  N.  Ach,  fiber  die  Willenstdtigkeit  und  das  Denken,  1905. 


THEORIES  OF  FEELING  AND  VOLITION  361 


(a)  Intelledualistic  Theories  of  Volition 

The  compelling  motive  in  the  intellectualistic  theories 
which  made  volition  dependent Lupon  cognition  has  been 
the  problem  of  the  freedom  of!  'the  will.  The  latter  has  it- 
self gone  through  many  changes.  The  conception  of  free- 
dom, a product  of  ancient  thought,  was  superseded  in  the 
Middle  Ages  by  the  unfathomable  controversies  as  to  the 
primacy  of  the  will  or  the  intellect,  until  in  modern  phi- 
losophy the  classical  period  of  the  problem  of  the  freedom 
of  the  will,  with  its  metaphysical  conception  of  freedom,  pre- 
pared the  way  for  the  transition  to  the  absolute  theories 
of  volition. 

(1)  THE  ANCIENT  CONCEPT  OF  FREEDOM 

The  concept  of  freedom  arrived  at  in  ethics  led  up  to 
the  question  of  the  motivation  of  actions.  Socrates  had 
connected  freedom  of  action  with  correct  knowledge  or 
insight.  Plato  at  first  maintained  a purely  psychological 
freedom  but  at  the  same  time  adhered  to  the  Socratic  con- 
tention that  the  bad  man,  wanting  in  right  knowledge,  does 
not  act  with  freedom.  Aristotle  arrived  at  a provisional 
conclusion  inasmuch  as  within  the  larger  psychological  di- 
vision of  willing  and  desiring  he  set  aside  voluntary  ac- 
tions as  the  subject-matter  for  ethics,  although  these  actions 
themselves  arise  from  a decision  deep-rooted  in  the  man 
himself.  The  deeper  underlying  problem  was  disclosed 
when  the  recognition  of  the  unity  of  all  natural  phenomena 
demanded  by  logic  came  into  opposition  with  the  freedom 
of  the  will  demanded  by  ethics.  This  happened  in  the  phi- 
losophy of  the  Stoics.  In  spite  of  all  attempts  to  save  the 
freedom  of  the  will  by  means  of  artificial  differentiation,  as, 
for  example,  that  of  Chrysippus  into  chief  and  secondary 


362 


HISTORY  OF  PSYCHOLOGY 


causes,  the  Stoics  generally  ended  in  an  unequivocal  deter- 
minism. 

One  thing  must  not  be  forgotten  in  this  survey  of  the 
ancient  theories  of  volition,  namely,  that  the  concept  of 
freedom  of  choice  in  the  sense  of  arbitrary  choice  was  quite 
foreign  to  them.  Absolute  freedom  of  choice,  which  baffles 
all  philosophical  comprehension,  points  clearly  to  that  period 
during  which  most  of  such  irrational  elements  found  their 
way  into  philosophy,  namely,  the  Patristic  period.  The 
dogmas  of  original  sin,  of  divine  grace,  and  of  predesti- 
nation demanded  kinds  of  freedom  different  from  that  be- 
queathed by  antiquity,  the  unequivocal  determination  of 
the  will  by  the  idea  of  the  good.  If  the  latter  contains  a 
non  posse  peccare,  then  mankind  must  also  have  a posse  non 
peecare  or  the  possibilitas  boni  et  mali.  These  are  the  dog- 
matic problems  of  the  famous  theory  of  freedom  of  Augus- 
tine, the  unavoidable  ambiguities  of  which  gave  rise  to  those 
endless  disputes  which  the  history  of  the  church  has  re- 
corded for  us. 

(2)  THE  PRIMACY  OF  WILL  OR  INTELLECT 

The  two  boundaries  between  which  Scholastic  theories  of 
will  moved  are  laid  down,  on  the  one  hand,  by  the  description 
of  the  will  as  a syllogismus  pradicus,  which  explains  will  as 
an  activity  of  the  intellect,  and,  on  the  other  hand,  by  the 
concept  of  the  actus  purus,  which  recognizes  the  will  as  an 
absolute  faculty.  In  the  important  discussion  as  to  the 
primacy  of  the  will  or  the  intellect  between  Thomas  Aquinas 
and  Duns  Scotus,  besides  metaphysical  and  dialectical  ap- 
peals, psychological  ones  were  also  introduced,  the  most 
important  of  the  former  being  that  of  intentional  relation- 
ship.1 Under  this  view-point  the  ranking  of  the  psychical 

1 Cf.  above,  pp.  74  /. 


THEORIES  OF  FEELING  AND  VOLITION 


363 


functions  was  determined  by  the  objects  to  which  they  re- 
ferred. The  will  aims  at  the  bonum,  the  intellect  at  the  verum. 
The  Thomists  placed  the  verum  above  the  bonum  and  from 
that  deduced  the  primacy  of  the  intellect  over  the  reason. 
The  Scotists  followed  the  converse  line  of  reasoning.  Or, 
again,  the  Thomists  maintained  that  the  intellect  seeks  the 
general  verum,  whereas  the  will  only  desires  the  special 
bonum.  The  Scotists  then  put  the  general  bonum  as  the 
object  of  the  will  and  in  this  way  retained  their  original  order 
of  values.  The  common  presuppositions  of  these  arguments, 
viz.,  that  the  real  effectiveness  of  the  functions  themselves 
corresponds  to  the  relative  value  of  the  psychical  functions 
and  these  again  to  the  order  in  rank  of  the  objects  to  which 
they  refer,  is  a striking  example  of  the  reaction  of  the  con- 
stitution of  the  outside  object  upon  the  conception  of  the 
psychical  processes,  a reaction  that  we  have  noticed  in 
several  other  places.1 

The  contrast  between  the  two  parties  is  seen  again  in 
the  problem  of  the  freedom  of  the  will.  The  Thomists 
declared  that  the  will  must  necessarily  strive  for  that  which 
is  recognized  as  good  by  the  intellect.  Of  psychological 
free  choice  there  remained  only  the  fact  that  the  will  de- 
cides upon  the  best  of  the  possibilities  shown  to  it  by  the 
intellect.  This  theory  logically  ended  in  intellectual  de- 
terminism in  Thomas  Aquinas.  Against  this  the  criticism 
of  his  opponents  was  naturally  directed.  They  unanimously 
declared  that  with  a will  dependent  in  this  manner  upon  its 
ideas  the  possibility  of  acting  otherwise,  and  therewith  all 
responsibility,  came  to  an  end.  Therefore,  Duns  Scotus 
reserved  for  the  will  the  freedom  of  choice  in  contradis- 
tinction to  the  impulses  or  desires  arising  from  pleasure  or 
pain  which  must  necessarily  follow  their  motives.2  Ideas 

1 Cf.  p.  144. 

2 Cf.  Siebeck,  Ztschr.  f.  Phil.  u.  phil.  Krit.,  Bd.  CXII,  p.  179. 


364 


HISTORY  OF  PSYCHOLOGY 


are  reduced  to  the  rank  of  occasional  causes.  In  the  more  or 
less  confused  mass  of  ideas  only  those  are  clearly  perceived 
upon  which  the  will  spontaneously  directs  its  attention  and 
by  so  doing  increases  their  intensity.  This  combination  of 
will  and  attention  was  a far-reaching  idea  which  was  not 
logically  followed  out  and  which  only  arose  again  in  modern 
theories  of  volition,  where  the  elementary  phenomenon  of 
volition  is  transferred  to  the  impulsive  apperception  of  an 
idea  of  movement.1 

Several  of  the  pupils  of  Duns  Scotus  tried  by  a slight 
approach  to  the  Thomistic  standpoint  to  tone  down  the 
blunt  autocracy  of  the  will,  which  with  their  master  had 
really  made  impossible  any  genuine  motivation.  Petrus 
Aureolus  supplied  the  will,  which  still  retained  the  capacity 
of  arousing  itself,  with  an  intellectual  activity  dependent 
upon  the  will  but  yet  knowing  the  aim  of  the  will.  The 
resulting  relationship  he  expressed  by  the  comparison  that 
the  sailor  at  first  moves  the  ship  and  this  having  become 
the  means  of  movement  in  its  turn  accidentally  moves  the 
sailor.  These  attempts  at  agreement  were  ruined  by  the 
accentuation  of  indeterminism  by  William  of  Occam.  He 
gave  the  problem  of  the  will  a new  view-point  inasmuch  as 
he  brought  the  affective  side  of  our  life  into  connection  with 
the  volitional  processes.  To  the  will  itself  he  ascribed  per- 
fect freedom  in  the  sense  of  arbitrary  choice.  The  acme, 
however,  is  reached  in  Buridan’s  theory  of  freedom,  which 
inaugurated  a new  epoch  in  the  treatment  of  the  problem 
of  the  will. 

(3)  THE  CLASSICAL  PERIOD  OF  THE  PROBLEM  OF  THE 
FREEDOM  OF  THE  WILL 

In  his  investigations  on  the  will  Buridan  brought  the 
traditional  theory  of  freedom  into  connection  with  the  be- 
1 See  below,  p.  370. 


THEORIES  OF  FEELING  AND  VOLITION 


365 


ginnings  of  a psychical  mechanism.1  The  will  is  not  a 
special  power  in  addition  to  the  intellect  but  rather  an  ac- 
tivity of  the  soul  proceeding  in  another  direction.  After  a 
judgment  as  to  the  acceptability  of  an  object  there  neces- 
sarily follows  pleasure  or  displeasure,  which  stimulates  the 
will.  To  the  latter  Buridan  gives  the  power  of  liberum 
arbitrium.  It  is  free  to  decide  when  the  motives  are  of 
exactly  equal  intensity.  There  is  no  such  thing  as  choice 
if  the  will  decides  for  the  good.  Now,  since  it  is  supposed 
to  do  this  by  necessity,  there  is  a contradiction  in  Buridan’s 
theory  of  the  will  which  is  to  some  extent  smoothed  over 
by  the  fact  that  true  freedom  lies  in  the  power  of  the  will 
to  keep  the  motives  before  the  intellect  long  enough  for 
true  insight  to  be  reached. 

At  any  rate,  Buridan  abandoned  the  idea  that  the  will 
could  decide  without  any  motives.  The  freedom  of  man  in 
comparison  to  the  non-freedom  of  animals  was  illustrated 
by  the  famous  picture,  ascribed  to  him,  of  the  donkey  that 
was  bound  to  die  of  hunger  if  placed  between  two  bundles 
of  hay  of  exactly  the  same  size. 

The  age  of  Buridan  and  his  immediate  successors  has 
been  called  the  classical  period  of  psychological  thought 
for  the  theory  of  the  will  from  the  time  of  Augustine 
to  Leibniz.  Occam’s  conception  of  freedom  as  the  undi- 
vided, that  is,  not  affected  by  more  or  less,  occurs  again  in 
Descartes’  Meditations.  His  indeterminism  is  just  as  much 
an  anticipation  of  Kant’s  doctrine  of  the  intelligible  charac- 
ter as  Buridan’s  opinion  of  freedom  as  the  libertas  finalis  or- 
dinationis  is  an  anticipation  of  the  Herbartian  conception  of 
“inner  freedom”  as  a harmony  between  insight  and  will. 
In  the  period  from  Descartes  to  Kant  the  problem  of  the 
freedom  of  the  will  remains  the  central  problem  in  the 

1 Cf.  Siebeck,  Beitrdge  zur  Entstehungsgeschichte  der  neueren  Psy- 
chologie,  1871. 


366 


HISTORY  OF  PSYCHOLOGY 


field  of  volitional  theory.  From  the  mass  of  attempted 
solutions  not  much  of  importance  has  resulted  for  psychol- 
ogy. Descartes’  theory  of  the  will  did  not  advance  beyond 
the  intellectualistic  standpoint  of  Scholasticism.  True  free- 
dom consists  herein:  with  imperfect  knowledge  to  restrain 
from  willing  and  with  perfect  knowledge  to  allow  that 
knowledge  to  work  as  the  decisive  motive.  The  attempt  to 
explain  psychologically  this  notion  of  freedom  came  to  grief 
in  the  theory  that  imperfect  knowledge  was  connected  with 
the  movement  of  the  nerve  spirits.1  All  this  resulted  in  the 
dominance  of  an  intellectualistic  ethics  and  a spiritualistic 
metaphysics.  Locke,  with  his  unpretentious  remark  that 
freedom  as  a faculty  cannot  possibly  be  attributed  to  the 
will,  itself  a faculty,  did  not  add  anything  to  the  psychology 
of  the  problem.  He  came  nearer  to  psychological  experi- 
ence when  he  allowed  uneasiness,  a feeling,  to  function  as 
a motive  for  the  will.  The  more  insistent  the  metaphysical 
side  of  the  problem  of  the  will  became  the  less  the  tradi- 
tional intellectualistic  theory  sufficed  to  give  a satisfactory 
solution. 


( b ) The  Absolute  Theory  of  the  Will 

All  the  difficulties  which  were  bound  to  overtake  an  in- 
tellectualistic theory  of  volition  were  solved  at  one  stroke 
by  the  absolute  theory  inasmuch  as  it  transformed  the  will 
into  a transcendental  faculty.  When  Kant  raised  this  pure 
will  to  the  rank  of  the  intelligible  character  of  man  he  not 
only  crowned  his  own  solution  of  the  problem  of  the  freedom 
of  the  will  but  he  also  pointed  the  way  for  future  meta- 
physics of  volition;  namely,  that  metaphysic  suggested  by 
Maine  de  Biran  which  triumphed  in  the  philosophy  of 
Schopenhauer  and  which  in  Hartmann  was  fused  with  the 

1 Les  passions  de  I’&me,  I,  arts.  47-50. 


THEORIES  OF  FEELING  AND  VOLITION 


367 


results  of  modern  science.  In  Schopenhauer’s  theory  of  the 
will,  which  follows  from  his  metaphysical  presuppositions, 
every  true  act  of  will  must  also  of  necessity  be  a move- 
ment of  the  body.  This  shuts  out  the  inner  acts  of  will  to 
which  there  corresponds  no  visible  movement  of  the  body. 
Through  an  obvious  misunderstanding  of  their  psychological 
peculiarities,  these  were  grouped  along  with  the  intellectual 
processes. 

The  invasion  of  the  field  of  empirical  psychology  by  a 
conception  of  the  will  partly  derived  from  logic  and  meta- 
physics is  already  seen  in  Beneke,  who  relegated  the  ten- 
dencies of  the  original  faculties  to  the  sphere  of  the  un- 
conscious.1 Later  on  Fortlage  saw  in  the  elementary  impulse 
the  solution  of  the  riddle  as  to  how  consciousness  arises  out 
of  unconscious  psychical  phenomena.2  The  impulse  antici- 
pates a subsequent  perception.  Its  immediate  satisfaction 
would  not  rise  to  consciousness.  But  as  soon  as  this  is 
postponed  there  arises  an  intermediate  state  of  doubt  or  of 
straining  of  the  attention,  i.  e.,  consciousness. 

A peculiar  use  of  the  absolute  theory  of  the  will  is  met 
with  in  several  physiologists  dealing  with  the  senses.  Hand 
in  hand  with  the  nativistic  explanation  of  spatial  percep- 
tion there  goes  the  belief  in  the  influence  of  pure  will  to 
carry  out  movements  of  the  eye,  and  this  is  supposed  to  be 
an  important  addition  to  the  contents  of  the  sensations.3 
In  their  mixture  of  physiological  and  transcendental  motives 
theories  of  this  kind  reflect  the  many-sided  nature  of  the 
problems  of  sense-perception. 

1 Cf.  0.  Kiilpe,  Wundts  Phil.  Stud.,  Bd.  V,  1889,  pp.  179,  381. 

2 System  der  Psychologie,  1855,  I,  pp.  53  ff. 

3 See,  for  example,  E.  Mach,  Beitrage  zur  Analyse  der  Empfindungen, 
1886,  p.  57. 


368 


HISTORY  OF  PSYCHOLOGY 


(c)  Heterogenetic  Theories  of  the  Will 

The  heterogenetic  theories  of  volition  arose  through  the 
influence  of  the  assistance  given  by  association  psychology. 
A unified  form  was  given  to  them  by  Herbart,1  for  whom 
each  idea  below  the  threshold  of  consciousness  changed 
itself  into  a striving  toward  an  idea.  The  experience  of 
desire  is  occasioned  when  the  rising  into  consciousness  of 
an  idea  is  hindered.  Suppose,  for  example,  an  idea  a is 
associated  with  a;  now  if  during  the  time  that  an  idea  /3 
opposed  to  a is  dominant  in  consciousness  a is  repro- 
duced by  a new  perception,  then  a is  at  one  and  the  same 
time  propelled  and  repelled,  and  in  so  far  as  it  is  surmount- 
ing the  resistance  it  is  desire  or  impulse.  If  to  this  desire 
fulfilment  is  added,  it  passes  over  into  volition  proper. 
Voluntary  movements  arise  by  means  of  the  associations  of 
feelings  with  perceived  movements. 

More  modern  attempts  to  derive  volitional  processes 
from  such  psychical  components  as  do  not  yet  contain  the 
peculiar  quality  of  striving  or  conation  can  be  grouped 
partly  under  the  purely  genetic  and  partly  under  the  physio- 
logical standpoint.  In  the  former  case  the  will  is  pictured 
as  a combination  of  idea  and  feeling,  as,  for  example,  in 
Th.  Waitz.2  Desire,  for  example,  is  the  unpleasant  feeling 
that  arises  when  some  pleasant  idea  is  at  the  same  time 
recognized  as  not  present  to  the  senses.  In  H.  Spencer 
the  simple  act  of  will  is  pushed  still  further  back  to  the  mental 
representation  of  the  act,  which  follows  the  actual  accom- 
plishment of  the  act.  The  complex  volitional  act  is  pre- 
ceded by  a reproduction  of  the  nervous  excitation  which 
actually  occurred  during  a former  action.  Since,  however, 

1 Lehrbuch  der  Psychologie,  Werke,  Hartenstein  ed.,  vol.  V. 

1 Lehrb.  d.  Psych.,  1849,  § 40,  pp.  417  ff. 


THEORIES  OF  FEELING  AND  VOLITION 


369 


this  itself  consisted  in  the  idea  of  a movement  combined 
with  feeling,  the  will  itself  consists  in  a reproduction  of  this 
idea. 

The  opposite  line  of  thought,  according  to  which  will  is  a 
development  of  feeling,  is  represented  in  the  standpoint  of 
Horwicz.1  For  him  feeling  is  the  elementary  psychical  proc- 
ess out  of  which  both  idea  and  will  have  been  developed. 
The  whole  development  of  the  will  is  traced  back  to  im- 
pulse, and  this,  according  to  Horwicz,  consists  of  a feeling 
of  pleasure  and  displeasure  which  shows  itself  in  move- 
ments.2 

Among  those  who  from  the  physiological  standpoint  have 
refused  to  admit  volitional  processes  as  elementary  psychical 
functions,  Miinsterberg3  has  been  one  of  the  most  influential. 
The  totality  of  physiological  processes  which  lead  up  to  an  act 
of  volition  forms  an  unbroken  chain  of  cause  and  effect,  and 
there  is  nowhere  any  room  for  the  introduction  of  a psychical 
factor.  According  to  his  fundamental  principle  that  sen- 
sations are  the  most  elementary,  unanalyzable  parts  of  con- 
sciousness,4 he  reduces  this  problem  to  the  question  as  to 
what  quality,  intensity,  and  feeling  tone  characterize  the 
sensations  making  up  our  will.  Following  the  first  hypoth- 
esis, he  comes  to  the  same  conclusion  as  Hobbes  and  con- 
siders all  volitional  processes  as  complicated  reflexes  and 
attempts  biogenetically  to  trace  the  evolution  of  voluntary 
acts  out  of  useful  reflexes.  His  second  hypothesis  leads 
him  to  take  the  decisive  step  of  analyzing  the  outer  volitional 
action  into  its  psychological  parts,  which  he  finds  to  be  sensa- 
tions of  innervation.  If,  before  a real  movement,  certain 
muscle  sensations  are  anticipated,  they  produce  the  con- 
scious state  called  willing. 


1 Zur  Entwicklungsgeschichte  des  Willens,  1876. 
3 Die  Willenshandlung,  1888. 


2 Cf.  p.  359. 
4 Cf.  p.  209. 


370 


HISTORY  OF  PSYCHOLOGY 


(d)  The  Emotional  Theory  of  the  Will 

The  starting-point  of  those  modern  theories  of  the  will 
which  take  into  account  the  affective  side  accompanying 
every  volitional  process  is  to  be  found  in  the  eighteenth 
century  in  David  Hume.  Very  probably  stimulated  by 
Shaftesbury’s  theory  of  the  emotions,  he  based  his  theory  of 
volition  upon  his  theory  of  the  emotions  in  the  clear  knowl- 
edge that  the  will  never  comes  into  being  without  a char- 
acteristic affective  accompaniment.1  In  the  nineteenth 
century  Bain  moved  along  similar  lines  of  thought,  for  he 
discovered  the  elements  of  volition  in  a spontaneous  activ- 
ity which  is  guided  by  feelings.  Every  pleasure  is  con- 
nected with  an  increase  and  every  pain  with  a decrease 
of  the  general  vital  functions.  The  connection  with  the 
feelings  of  certain  outer  activities  calling  forth  pleasure  and 
avoiding  pain  is  then  explained  from  the  standpoint  of  as- 
sociation psychology. 

The  further  development  of  the  emotional  theory  of 
volition  was  partly  determined  by  the  general  classification 
of  the  contents  of  consciousness.  If  only  two  kinds  of 
psychical  elements  are  supposed  to  exist — feelings  and  sen- 
sations— then  it  is  necessary  to  show  the  affective  elements 
contained  in  our  volitional  experiences.  Along  these  lines 
lies  Wundt’s  theory  of  volition,  in  which  feeling,  emotion, 
and  will  form  progressive  stages  of  processes  that  belong 
together,  and  in  which  the  apperception  of  a psychical 
content  is  held  to  be  the  elementary  form  of  a volitional 
process.  The  outer  volitional  act,  regarded  as  a phenom- 
enon of  consciousness,  becomes  nothing  else  than  an  im- 
pulsive apperception  of  an  idea  of  movement. 

T.  Lipps  arrived  at  another  form  of  emotional  theory  of 
1 A Treatise  of  Human  Nature , bk.  II,  part  III,  sect.  III. 


THEORIES  OF  FEELING  AND  VOLITION 


371 


volition.  According  to  the  requirement1  made  by  him  of 
adding  to  every  content  of  consciousness  the  real  psychical 
process  appearing  in  it,  we  postulate,  on  the  basis  of  the 
experienced  feeling  of  effort,  a real  psychical  process  of  effort 
or  striving  which  represents  a psychical  activity  that  is 
hindered  or  overcomes  hindrances  in  its  natural  progress. 
The  result  of  such  a hindrance  is  pictured  as  a blocking, 
which  results  in  an  increase  of  the  psychical  activity.  Here 
Lipps  is  following  precisely  in  the  spirit  of  Herbart’s  psychical 
mechanics.  His  endeavor  at  first  had  been  to  transplant 
the  Herbartian  ideas  from  the  realm  of  metaphysics  to  the 
region  of  experience,2  but  this  was  abandoned  after  an 
insight  into  the  insolubility  of  such  problems.  Now  Lipps 
recognizes  it  as  incomprehensible  how  it  happens  that  we 
experience  in  outer  volitional  action  the  bodily  activity  as 
our  own  activity;  we  have  no  insight  into  the  manner  in 
which  the  bodily  sensations  might  arise  out  of  such  an 
activity.  Instead  of  the  influence  of  the  soul  upon  the 
body,  we  must  postulate  a real  psychical  process  which  cor- 
responds to  an  unknown  bodily  process,  and  thus  the  psy- 
chology of  Lipps  ends  again  in  metaphysics. 

In  contrast  to  these  emotional  theories  we  find  in  most 
recent  times  an  attempt  to  reduce  the  phenomena  of  voli- 
tion to  the  facts  of  reproduction  and  association,  and 
chiefly  to  the  so-called  persevering  and  determining  ten- 
dencies. This  opinion  is  held  by  Kiilpe  and  the  psycholo- 
gists of  his  school,  and  has  been  investigated  experimen- 
tally. The  discovery  of  the  determining  tendencies  seems 
to  point  to  a new  concept  that  will  be  of  the  greatest  im- 
portance in  this  branch  of  psychology.3  A similar  line  of 
thought  is  found  in  the  volitional  theory  of  Meumann,  who 

1 See  p.  43. 

2 Grundtatsachen  des  Seelenlebens,  pp.  19  if.,  594  ff. 

3 Cf.  N.  Ach,  Uber  den  Willensakt  und  das  Temperament,  1910;  on 
the  introduction  of  the  term  “determination,”  see  p.  286. 


372 


HISTORY  OF  PSYCHOLOGY 


considers  the  chief  part  of  the  volitional  process  to  be  the 
phenomenon  of  selection  that  is  occasioned  by  approved 
ideas  directed  toward  a certain  end.1 

1 E.  Meumann,  Intelligenz  und  Wille,  1908,  p.  191. 


INDEX  OF  NAMES 


Aeh,  N.,  136,  137,  211,  360,  371. 
Agrippa  of  Nettesheym,  56. 
Aguillonius,  F.,  283,  324. 

Albert  von  Bolls  tadt,  172. 
Albertus  Magnus,  272,  334. 
Alcuin,  21. 

d’Alembert,  149,  158,  311. 
Alexander  of  Aphrodisias,  73,  168, 
281,  282,  334. 

Alexander  of  Hales,  54. 

Alhacen,  7,  317,  318,  319,  320,  325. 
Amerbach,  75. 

Ampere,  65. 

Anaxagoras,  16,  17,  26. 

Angell,  165. 

Anselm  of  Canterbury,  75. 
Aquinas,  9,  22,  54,  74,  75, 169, 179, 
194,  362,  363. 

Arago,  132,  238. 

Aresas  of  Croton,  47. 

Aristotle,  5,  7,  8,  18,  19,  21,  26,  27, 
48,  50,  54,  56,  60,  68,  72,  73,  74, 
89,  90,  149,  167,  169,  179,  180, 
182, 193,  200,  269,  271,  273,  274, 

280,  281,  284,  285,  286,  298,  317, 
324,  347,  348,  350,  352,  361. 

Armatus,  Salvinus,  323. 

Arnobius  of  Sicca,  35. 

Aubert,  292. 

Augustine,  20,  50,  74,  168,  193, 

281,  316,  362,  365. 

Augustus,  91. 

Aureolus,  364. 

Avenarius,  163. 

Averroes,  21. 

Avicenna,  53,  54,  74,  91. 

Bacon,  Francis,  3,  36,  148,  149. 
Bacon,  Roger,  55. 

Baeumker,  271,  334. 

Bain,  Alex.,  102,  161,  175,  180, 
204,  335,  340,  348,  370. 


Baldwin,  J.  M.,  10,  11,  139. 
Barach,  52. 

Bastian,  41. 

Baumgarten,  78,  99. 

Becker, lJ.  J.,  147. 

Bell,  C.;  229. 

Bendavid,  L.,  313. 

Bendixen,  230. 

Beneke,  67,  81,  156,  178,  180,  367. 
Bergemann,  88. 

Berkeley,  27,  28,  76,  77,  161,  199, 
325,  328,  334,  335. 

Bernouilli,  224,  225,  240,  321. 
Bernstein,  246,  247. 

Bessel,  131. 

Biunde,  80. 

Blix,  342. 

Boerhave,  120. 

Boethius,  72. 

Bonacursius,  287. 

Bonatelli,  128. 

Bonnet,  62,  77,  94,  96,  120,  183, 
184,  186,  275,  276,  353. 
Bouguer,  237,  238. 

Boyle,  272,  284. 

Brentano,  82,  84,  85, 154, 159,  160, 
161, 163, 175, 178, 179, 180,  200, 
201,  202,  205,  248,  260,  349. 
Brett,  10. 

Brewster,  288. 

Broca,  122. 

Brown,  100,  196. 

Brucke,  125,  330. 

Buchner,  40. 

Buffon,  61,  288. 

Burdach,  30. 

Buridan,  91,  182,  236,  282,  353, 
364,  365. 

Burnet,  15. 

Cabanis,  28. 

Cardanus,  288. 

373 


374 


INDEX  OF  NAMES 


Carus,  C.  G.,  30,  67,  114. 

Cams,  F.  A.,  8. 

Casmann,  22,  57,  75. 

Castel,  285. 

Chrysippus,  361. 

Chun,  278. 

Cicero,  91. 

Clauberg,  58. 

Cleomedes,  279. 

Cohen,  159. 

Comte,  81,  82,  154,  215,  217. 
Condillac,  28,  77,  113,  114,  186, 
199,  297,  328. 

Confucius,  309. 

Constantine  of  Carthage,  52. 
Cornelius,  102,  163. 

Cotes,  224. 

Cotugno,  298. 

Cousin,  51,  53. 
v.  Craanen,  93. 

Creighton,  115. 

Crusius,  61. 

Czermak,  342. 

Czolbe,  40. 

Damascenus,  52. 

Darwin,  115,  116,  229,  277. 

Davy,  281. 

Delbceuf,  248,  249,  250,  253,  256. 
Delezenne,  241. 

Democritus,  5,  33,  34,  37,  47,  145, 
280,  334. 

Descartes,  7,  22,  23,  36,  51,  58,  60, 
76,  93,  113,  120,  154,  161,  169, 
170,  274,  275,  321,  322,  353, 
365,  366. 

Dessoir,  9,  10,  57,  98. 

Dicsearchus,  34,  49. 

Diderot,  38,  39,  99,  149,  150. 
Digby,  120. 

Dilthey,  210. 

Diodorus  of  Tyre,  49. 

Diogenes  of  Apollonia,  33,  88, 
181. 

Dionysos,  16. 

Domrich,  348,  355. 

Donders,  125,  133. 

Drobisch,  107. 

Dunn,  325. 


Duns  Scotus,  31,  55, 194,  362,  363, 
364. 

Durr,  157. 

Ebbinghaus,  2,  207,  213,  219. 
Eberhard,  234. 

Eckhart,  8,  194. 

Edwards,  139. 

Ellis,  299. 

Empedocles,  15,  273,  280. 
Epicurus,  34,  35,  36,  280. 
Erdmann,  68,  156. 

Eschenmayer,  235. 

Esteive,  311. 

Euclid,  279,  325. 

Euler,  309,  310. 

Ewald,  307,  308. 

Exner,  68. 
v.  Eyck,  323. 

Fechner,  99,  110,  125,  129,  130, 
133, 138, 175, 178,  218,  219,  220, 
221,  222, 223,  226,  227,  228,  232, 
234,  239,  240,  242,  243,  244,  245, 
246, 249,  252, 253,  254,  255,  257, 
259,  261,  262,  263,  266, 267, 288. 
Feder,  117. 

Fer6,  229,  230. 

Fichte,  J.  G.,  104,  114,  170,  171, 
174. 

Fichte,  J.  H.,  30. 

Fischer,  30. 

Fischer,  K.,  9,  30. 

Fisher,  10. 

Flammarion,  3. 

Flourens,  121. 

Fortlage,  81,  367. 

Fortuninus  Licetus,  36. 

Fouille,  185. 

Fourier,  308. 
v.  Frey,  343. 

Fries,  64,  104. 

Fritsch,  123. 

Galen,  48,  52,  57,  74,  168,  323. 
Galileo,  2,  269,  272. 

Galin,  241. 

Gall,  121,  154,  215. 

Galuppi,  235. 


INDEX  OF  NAMES 


375 


Gasparin,  3. 

Gassendi,  36,  37,  325. 

Gauss,  225,  226. 

Geiger,  115. 

George,  199,  339,  351. 

Gerhard,  173. 

Gerhardt,  233. 

Gladstone,  115. 

Gockel,  22,  147. 

Goethe,  284,  285,  286,  292. 

Goltz,  277. 

Gouye,  325. 

Gregory  of  Nyssa,  20,  50. 

Gruithuisen,  143. 

Haas,  279. 

Haeckel,  41. 

Hagen,  355. 

Haller,  117,  120,  321. 

Hamann,  153. 

Hamilton,  83,  101,  156,  173,  176, 
184, 187, 188, 197,  200,  201,  215. 

Harless,  298,  299. 

Hartenstein,  104,  368. 

Hartley,  38,  92,  93,  94,  95,  103, 
161,  199. 

v.  Hartmann,  9, 114, 132, 174, 176, 
366. 

Hasner,  332. 

Hasse,  302. 

Hauser,  288. 

Hegel,  67,  68,  351. 

Heinrich  von  Hessen,  272. 

Heinroth,  30. 

Helmholtz,  124, 125, 126, 127, 132, 
133, 174,  176, 177,  245,  277,  287, 
288,  290,  291,  292,  293,  294,  297, 
299,  300,  301,  302,  303,  304,  305, 
306,  307,  308,  311, 312,  313,  333, 
335,  336. 

van  Helmont,  57. 

Hensen,  302,  304. 

Heraclitus,  14,  15,  17,  281. 

Herbart,  29,  30,  65,  66,  67,  80,  90, 
103, 104, 105, 106, 107, 108,  110, 
111,  122, 124, 151, 153, 161,  174, 
179, 182, 185, 197, 199,  201,  208, 
210,  214,  298,  337,  338, 353,  354, 
368,  371. 


Herder,  99,  117,  153. 

Hering,  117,  249,  250,  251,  256, 
260,  261,  292,  293,  294,  295,  296, 
331,  332,  333. 

Hermann,  304,  305,  306,  331. 
Herophilus,  48. 

Her  os,  279. 

Herschel,  238. 

Herz,  97,  153. 

Heymans,  265. 

Hickok,  139. 

Hilary  of  Poitiers,  35. 

Hipparchus,  238. 

Hirsch,  132. 

Hissmann,  62,  95. 

Hitzig,  123. 

Hobbes,  36,  37,  76,  92,  214,  369. 
Hoffbauer,  97. 

Hoff  ding,  102,  137,  169. 

Holbach,  38. 

Home,  99. 

Horwicz,  216,  217,  277,  348,  359, 
369. 

Huarte,  57. 

Hugo  of  St.  Victor,  21. 

Hume,  31,  76, 77,  92, 170, 186, 196, 
199,  214,  351,  370. 

Husserl,  85,  157,  189,  205,  206. 

Irwing,  62,  96. 

Isaac  of  Stella,  21. 

Itelson,  233. 

de  Jaager,  133. 

Jager,  41,  116. 

Jakob,  97. 

James,  229,  357. 

Jesus,  18. 

Jodi,  206,  349. 

John  of  Salisbury,  53. 

Jouffroy,  65. 

Judd,  13. 

Jurin,  288,  326. 

Kant,  9,  28,  31,  39,  40,  63,  64,  79, 
97,  100,  104,  124,  150,  151,  152, 
153,  156,  161, 170, 196,  200,  203, 
234,  275,  326,  351,  365,  366. 
Kepler,  272, 283, 320, 321, 323, 324. 


376 


INDEX  OF  NAMES 


Kinnebrook,  131. 

Ivircker,  287,  309. 

Kirnberger,  241. 

Knutzen,  151. 

Koenig,  304,  305. 

Kolliker,  329. 

Krause  23 

von  Kries,  255,  256,  266,  291,  293, 
294,  295,  296. 

Krueger,  F.,  270,  314,  315. 

Krug,  63,  197. 

Kulpe,  108,  349,  352,  367,  371. 
Kurella,  229. 

Lacaille,  237. 

Lactantius,  281. 

Ladd  Franklin,  295. 

Lagrange,  224,  304. 

Lamarck,  114. 

Lambert,  117,  224.  226,  236,  237. 
Lamettrie,  38. 

Lancisi,  120. 

Lange,  C.,  229,  230,  357. 

Lange,  F.  A.,  33,  81,  82,  176. 
Langer,  250. 

Laplace,  226,  240. 

Laromiguiere,  186. 

Lazarus,  111. 

Lehmann,  102,  230. 

Leibniz,  9,  27,  28,  29,  59,  60,  77, 
104, 117,  139, 147, 171,  172, 173, 
177, 185,  199,  214,  233,  234,  310, 
351,  365. 

Lelut,  80. 

Leuckart,  278. 

Lewes,  174,  176,  203,  277. 

Liebig,  126. 

Linn6,  61. 

Lipps,  G.  F.,  224,  228,  267. 

Lipps,  T.,  31,  43,  100,  110,  175, 
205,  264,  265,  310,  315,  344,  345, 
349,  370,  371. 

Listing,  125. 

Locke,  7,  27,  58,  59,  60,  72,  76,  77, 
83,  92,  160,  169,  173,  182,  184, 
186, 195, 196, 198,  203,  271,  272, 
275,  326,  328,  334,  350,  366. 
Loeb,  42,  115. 

Lossius,  62,  95,  96,  187,  297. 


Lotze,  30,  100,  108,  110,  175,  180, 
197,  198,  200,  201,  329,  340,  341, 
342,  344,  356. 

Lubbock,  112. 

Lullus,  147,  148. 

Maass,  98. 

Mach,  134, 163, 246,  253,  292,  307, 
367. 

Magendie,  121. 

Magnus,  116. 

Maine  de  Biran,  28,  29,  366. 
Malebranche,  92, 93, 173, 233, 284, 
334. 

Mantegazza,  41. 

Marbe,  137. 

Mariotte,  321. 

Marpurg,  241. 

Martineau,  154. 

Maskelyne,  131. 

Masson,  238. 

Maudsley,  82,  174,  176,  215,  216. 
Maupertuis,  39. 

Maximus  of  Tyre,  90. 

Maxwell,  3. 

Meiners,  78. 

Meinong,  266. 

Meissner,  342. 

Melanchthon,  147. 

Mendelssohn,  151,  196. 

Merkel,  222. 

Methodius  of  Tyre,  35. 

Metzner,  343. 

Meumann,  371,  372. 

Meyer,  J.  B.,  150. 

Meyer,  M.,  306. 

Meynert,  94,  122,  356. 

Michalski,  3. 

Michelet,  68. 

Mill,  J.,  101,  173,  335,  348. 

Mill,  J.  S.,  82,  96,  101,  126,  127, 
156,  160,  175,  180,  215,  335, 
348. 

Mittenzwey,  185. 

Moleschott,  40. 

Molyneux,  325,  326. 

Montaigne,  57. 

Moritz,  118. 

Mosso,  229,  230. 


INDEX  OF  NAMES 


377 


Muller,  F.  A.,  254. 

Muller,  G.  E.,  219,  227,  228,  232, 
257,  259,  260,  261,  262,  296. 
Muller,  J.,  124,  125, 126,  132,  276, 
277,  298,  323,  324,  326,  327,  330, 
333,  356. 

Muller,  J.  J.,  251,  252. 

Munk,  122, 

Mtinsterberg,  162,  208,  209,  369. 

Nagel,  A.,  330. 

Nagel,  W.,  278. 

Nahlowsky,  348. 

Natorp,  158,  189. 

Nemesius,  20,  274. 

Nero,  323. 

Newton,  214,  284,  285,  286,  288, 
290. 

Notker,  72. 

Nuguet,  285. 

Occam,  55,  364,  365. 

Opelt,  310. 

Origen,  19. 

van  der  Paele,  323. 

Panum,  125,  331,  333. 

Paracelsus,  56,  57,  283. 

Parinaud,  294. 

Parmenides,  88. 

Paulsen,  31. 

Philo,  18,  50,  75. 

Plateau,  222,  248,  249,  260,  288, 
289. 

Plato,  14,  17, 18,  20,  23,  47,  48,  56, 
69,  72,  89,  144,  145,  167,  193, 
214,  317,  361. 

Plattner,  96,  120,  161. 

Pliny,  281,  323. 

Plotinus,  19,  20,  91,  168,  281. 
Ploucquet,  117,  233. 

Poincare,  10. 

Poisson,  240. 

Porphyry,  20,  274. 

Porro,  3. 

Porta,  320,  323. 

Porter,  139. 

Porterfield,  330. 


Preyer,  117. 

Priestley,  38. 

Prieur  de  la  Cote-d’Or,  288. 
Ptolemy,  279,  324. 

Purkinje,  124. 

Pythagoras,  308,  352. 
Pythagoreans,  15,  308. 

Rfidl,  41,  113. 

Rameau,  311. 

Ranke,  278. 

Rehmke,  163,  210. 

Reid,  196. 

Reimann,  324. 

Reimarus,  113,  115,  151. 

Reinhold,  64. 

Renz,  223. 

Rhode,  17. 

Ribot,  9,  11,  356. 

Rickert,  162. 

Riehl,  157. 

Romieu,  311. 

Rosenkranz,  40,  68. 

Rumford,  289. 

Sauveur,  311. 

Scaliger,  283. 

Schaefer,  308. 

Scheiner,  320. 

Schelling,  7,  30,  67,  114,  124,  127, 
174. 

Scherffer,  288. 

Scheuchzer,  98. 

Schleicher,  116. 

Schleiden,  331. 

Schmucker,  139. 

Schneider,  254. 

Schopenhauer,  31,  114,  286,  366, 
367. 

v.  Schubert,  30,  68. 

Schultze,  294. 

Schulze-dSnesidemus,  65,  80. 
Schutz,  234. 

Scotus  Erigena,  74. 

Seebeck,  299. 
von  Selpert,  121. 

Seneca,  171. 

Sennert,  35. 

Shaftesbury,  370. 


378 


INDEX  OF  NAMES 


Siebeck,  8,  9,  21,  51,  52,  53,  54,  55, 
90,  168,  193,  317,  363,  365. 
Sigwart,  157. 

Simon  Portius,  283. 

Simonides,  91. 

Simpson,  224. 

Smith,  288,  325,  326. 

Socrates,  18,  361. 

Sommer,  351. 

Sophia  Charlotte,  38. 

Sorge,  303. 

Speck,  94. 

Spencer,  41,  103,  112,  140,  154, 
161,  175,  199,  204,  368. 

Spinoza,  25,  38,  124,  161,  214. 
Steinbuch,  339. 

Steinheil,  223,  239. 

Steinthal,  111. 

Stern,  118. 

Stoics,  34, 35, 49, 171, 282, 361, 362. 
Strato,  34,  73. 

St’:unz,  57. 

Stumpf,  124,  206,  312,  313,  314, 
315,  333. 

Sugruta,  279. 

Sulzer,  241. 

Tartini,  311. 

Telesius,  283. 

Tertullian,  35,  50. 

Tetens,  62,  78,  153,  196. 
Theophrastus,  273,  280. 

Thomas,  33. 

Thury,  3. 

Tiberius,  288. 

Titchener,  115,  194,  357,  359. 
Toland,  37. 
du  Tour,  323. 

Tso-kiu-ming,  309. 

Tumarkin,  99. 

Tylor,  112. 

Uberhorst,  248. 
tiberweg,  82. 

Ulrici,  80,  175,  177,  180,  254,  255. 

Valentin,  143. 

Vico,  112. 

Vierordt,  134,  135,  223. 


da  Vinci,  289,  292. 

Virchow,  41. 

Vitellio,  325. 

Vives,  7,  56,  92,  169. 

Vogt,  41. 

Voigt,  305. 

Volkelt,  137. 

Volkmann,  A.  W.,  125. 

Volkmann,  W.  F.,  9, 108,  200,  348. 

Waetzmann,  308. 

Wagner,  41. 

Waitz,  107,  338,  348,  351,  368. 
Waldeyer,  302. 

Waller,  290. 

Wasmann,  115. 

Watson,  165. 

Weber,  E.  H.,  127,  130,  220,  221, 
239,  240,  242,  244,  328,  329,  330, 
342,  356. 

Weber,  W.,  129. 

Weigel,  72. 

Weininger,  118. 

Weiss,  104. 

Wheatstone,  325. 

William  of  Conches,  52. 

Willmann,  192. 

Willy,  163. 

Windelband,  135,  157. 

Wirth,  131,  181,  188,  264. 

Witelo,  317. 

Wolf,  223. 

Wolff,  7,  59,  60,  61,  78,  147,  150, 
196,  203,  217,  233,  234,  351. 
de  Wulf,  6. 

Wundt,  4,  9,  13,  31,  32,  44,  102, 
111,  112,  115,  123,  133, 134, 135, 
153,  157,  162,  163,  175, 180, 185, 
207,  210,  217,  218,  219,  232,  250, 
254,  257,  262,  263,  265,  294,  295, 
320,  343,  344,  349,  358,  370. 

Young,  277,  290,  294,  304. 

Zahlfleisch,  281. 

Zeller,  255. 

Zeno,  352. 

Ziehen,  94. 

Zollner,  174,  176. 


INDEX  OF  SUBJECTS 


Analysis,  principle  of,  202-5. 

Association,  doctrine  of,  87-103; 
beginnings  of  association  psy- 
chology, 88-92;  dominance  of 
doctrine  of,  92-103. 

Attention,  184-9. 

Audition,  theories  of,  297-315. 

Classification  of  contents  of  con- 
sciousness, principles  of,  191- 
205;  modem  forms  of,  205-7. 

Color  theories,  modern,  287-296; 
three-color  theory,  290-2;  four- 
color  theory,  292-6. 

Consciousness,  166-189;  history 
of  the  concept  of,  166-172;  early 
development  of  the  concept  of, 
166-9;  modern  concept  of,  169- 
172;  range  of,  181-4;  gradua- 
tion of,  184-9;  classification  of 
contents  of,  190-211. 

Consonance  theories,  308-315. 

Contents  of  consciousness,  classi- 
fication of,  190-211. 

Darwinism,  influence  of,  115-117. 

Dualism,  14-24. 

Empiricism,  333-6. 

Error,  theory  of,  222-9;  Gauss’s 
Law  of,  225. 

Faculties,  doctrine  of  mental,  44- 
69;  newer  psychology  of,  58-69. 

Feeling,  theories  of,  346-359;  in- 
tellectualistic,  350-1 ; physi- 
ological, 355-7;  psychomechan- 
ical, 352-5;  psychophysical, 
358-6. 

Freedom,  ancient  conception  of, 
361-2;  of  the  will,  364-6. 

Fusion  theory,  Herbart’s,  337-8. 


Ideas,  mechanics  of,  103-111. 

Inner  sense,  doctrine  of,  69-86; 
older  doctrine  of,  5,  72-76;  as 
an  independent  source  of  experi- 
ence, 76-82;  relation  of,  to 
theory  of  knowledge,  82-86. 

Intentional  relationship,  principle 
of,  200-2. 

Introspection,  212-215. 

Light,  ancient  theories  of,  279-283. 

Local  sign  theories,  340-5. 

Materialism,  32-42;  atomistic, 
33-36;  mechanistic,  36-38;  psy- 
chophysical, 38-40. 

Measurement,  psychical,  232-267; 
development  of  methods  of, 
218-231;  early  history  of,  232- 
242;  earliest  suggestions  of, 
242-4;  founding  of,  by  Fechner, 
242-4;  new  foundation  of,  257- 
267. 

Methods,  psychophysical,  212- 
231;  older  forms  of,  220-2;  ex- 
pression, 229-231. 

Monism,  25-42. 

Nativism,  326-333. 

Nativistic  theories,  330-3. 

Non-derivability,  principle  of,  194- 

200. 

Observation,  212-215. 

Occult,  relation  to  modern  psy- 
chology, 3. 

Optics,  physical  and  physiological, 
283-7. 

Perception,  spatial,  theories  of, 
315-345;  special  problems  of, 
322-6. 


379 


3S0 


INDEX  OF  SUBJECTS 


Phenomena,  differentiation  of 
physical  from  psychical,  159- 
163. 

Philosophy,  relation  to  psychology, 
156-9. 

Phrenology,  119-123. 

Physiology,  of  the  senses,  influ- 
ence of,  123-7 ; as  basis  of  psy- 
chology, 215-218. 

Psychical  element,  concept  of, 
210-211. 

Psychologism,  156-9. 

Psychology,  general  characteris- 
tics of  the  history  of,  1-2;  occult, 
relation  to  modem,  3;  applica- 
tions of,  4;  beginnings  of  mod- 
em, 7-8;  bibliography  of  his- 
tory of,  8-11;  dualism  in,  14— 
24;  metaphysical  and  empirical 
tendencies  in,  12-14;  monism  in, 
25-42;  descriptive,  43-86;  ex- 
planatory, 87-140;  as  a mechan- 
ics of  ideas,  103-111;  compara- 
tive, 111-118;  ethnic,  111-113; 
animal,  113-115;  individual,  117- 
118;  experimental,  127-140;  de- 
velopment of  the  fundamental 
concepts  of,  141-267 ; idea  of,  as 
a science,  141-165;  older  concep- 
tual formulations  of,  147-150; 
problem  of  a science  of,  150-5; 
modem  concept  of,  155-165; 
and  philosophy,  156-9;  and 
natural  science,  159-165. 

Psychophysics,  245-257  ;'objections 
to  Fechner’s,  245-252;  philo- 
sophical opponents  of,  254-7. 

Renaissance,  56-58. 

Resonance,  preliminary  history  of 
theory  of,  297-9;  theory  of, 


299-303;  further  developments 
of  theory  of,  304-8. 

Scholasticism,  50-55. 

Science,  influence  of  natural,  119- 
140;  psychology  as  a,  141-165; 
natural,  and  psychology,  159- 
165. 

Sensation,  theories  of,  268-315; 
older  theories  of,  273-5. 

Soul,  conception  of,  12;  doctrine 
of  the  parts  of,  46-50. 

Space,  empirical  theories  of,  334-5; 
Helmholtz’s  theory  of,  335-6; 
genetic  theories  of,  337-345. 

Specific  energy  of  the  nerves, 
theory  of  the,  275-8. 

Spiritualism,  26-32. 

Theories,  psychological,  268-372. 

Touch,  in  spatial  perception,  327- 
330. 

Unconscious,  concept  of,  172-181; 
representatives  and  opponents 
of  the  concept  of  the,  172-5; 
arguments  for  and  against,  175- 
181. 

Vision,  theories  of,  279-296. 

Volition,  theories  of,  359-372;  in- 
tellectuaJistic  theories  of,  361-6. 

Weber’s  Law,  235-242;  psycho- 
logical interpretation  of,  262-7. 

Will,  absolute  theory  of  the,  366-7 ; 
heterogenetie  theories  of  the, 
368-9;  emotional  theory  of  the, 
370-2. 


UUU/' 


150 
K64H 

Klomm,  0. 

A history  of  psychology 

150  K6 *(i  ' 703?8 


